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Polycystic ovary syndrome (PCOS) is the most common cause of anovulatory infertility; however, whether women with PCOS and spontaneous or drug-induced ovulatory cycles have the same reproductive potential as non-PCOS controls is a matter of debate. In the present opinion paper, the author takes the opportunity to summarize the collective evidence supporting the hypothesis of reduced fertility potential in women with PCOS, regardless of ovulatory status, and speculate that reduced reproductive potential may be caused by altered oocytes, embryo and endometrial competence, and infertility-related co-morbidities as well as an increased risk of pregnancy complications. [ABSTRACT FROM AUTHOR]

Study Question: What are the best practices for undertaking epidemiologic and phenotypic studies in polycystic ovary syndrome (PCOS)?Summary Answer: Best practices for the undertaking of epidemiologic and phenotypic studies in PCOS are outlined.What Is Known Already: Currently methodologies used for studies of PCOS epidemiology and phenotypes vary widely, and the comparability of studies is low, reducing the ability to harmonize studies.Study Design, Size, Duration: The Androgen Excess and PCOS (AE-PCOS) Society established a Task Force to draft a research resource for epidemiologic and phenotypic studies in PCOS, with the aim of providing guidelines on study design and execution, insights into the limitations and alternatives and protocols to be used, taking into consideration a global perspective.Participants/materials, Setting, Methods: A targeted review of the literature was carried out as necessary.Main Results and the Role Of Chance: High level recommendations include the following: (i) Before initiating the study, a number of critical factors should be addressed including selecting the population and diagnostic criteria (which should ideally align with the recommendations of the International Guidelines), the type of observational study to be undertaken and the primary and secondary endpoint(s) of the study.(ii) To assess the 'natural' or true phenotype and epidemiology of PCOS, the least medically biased, broadest and most generalizable population, and the broadest definition of PCOS, should be used.(iii) Four PCOS phenotypes (Phenotypes A through D), based on the presence or absence of three general features (oligo-anovulation, hyperandrogenism and polycystic ovarian morphology), should be ascertained.(iv) In epidemiologic and phenotypic studies, the detection of PCOS rests on the accuracy and sensitivity of the methods used for assessing the individual features of the disorder, and how 'normal' is defined.(v) Although an assessment algorithm that minimizes the use of certain measures (e.g. androgen levels and/or ovarian ultrasonography) can be devised, when possible it is preferable to uniformly assess all subjects for all parameters of interest.(vi) The inclusion of subjects in epidemiologic studies who do not appear to have PCOS (i.e. 'non-PCOS') will provide the necessary cohort to establish population-specific normative ranges for the various features of PCOS. (vii) Epidemiologic studies of PCOS in unselected populations will yield relatively limited numbers of PCOS subjects available for genetic study; alternatively, large population-based epidemiologic studies of PCOS will potentially generate large numbers of unaffected individuals that may serve as genetic controls. (viii) Epidemiologic studies of PCOS will benefit from a clear governance structure and should begin by informing, educating and engaging both the formal and informal leaders of the populations targeted for study. (ix) In designing their study investigators should, in advance, establish statistical power and recognize, manage and account for inherent biases. (x) Subjects suspected of having PCOS but who do not/cannot complete their evaluation (i.e. have 'possible PCOS') can be included by imputation, assigning them a 'diagnostic weight' based on those subjects of similar clinical phenotype that have completed the study. (xi) In obtaining, storing and retrieving subject data, subjects should be assessed consecutively using a uniform data collection form; providing as complete and in depth data as possible. (xii) Maintenance of both paper and electronic medical records should focus on ensuring data quality, accuracy and institutional ethical compliance, and familiarity with country-dependent laws, including biobanking-specific laws, tissue laws and research laws. (xiii) In obtaining and biobanking study samples, these should be ideally collected at the time of the first assessment. (xiv) Access to stored data sets should ideally be granted to other bona fide researchers conducting research in the public interest. (xv) SOPs detailing the exact method of each of the activities for handling the data and the samples are necessary to ensure that all methods are performed uniformly. (xvi) Epidemiologic studies of PCOS must be resourced adequately.Limitations, Reasons For Caution: As with all reports involving expert interpretation of experiential and published data, inherent individual biases are possible. This risk is minimized in the present study by including experts from varying fields of study, aligning with recent international evidence-based guidelines and obtaining consensus approval of the recommendations from the Task Force and the board of the AE-PCOS.Wider Implications Of the Findings: These guidelines should encourage investigators worldwide to undertake much needed epidemiologic studies of PCOS, increasing the validity, integrity and comparability of the data.Study Funding/competing Interest(s): The study received no funding. R.A. serves as consultant for Medtronic, Spruce Biosciences and Ansh Labs; has received research funding from Ferring Pharmaceuticals; and is on the advisory board of Martin Imaging; R.L. has received research funding from MSD Pharmaceuticals; J.L. has received fees and/or grant support from the Dutch Heart Association, The Netherlands Organisation for Health Research and Development (ZonMw), Ferring Pharmaceuticals, Danone, Euroscreen/Ogeda and Titus Health Care; H.T. receives grant funding from the National Health and Medical Research Council; K.K., L.M.-P., S.S.M. and B.O.Y. have no potential conflicts of interest.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

In vitro maturation (IVM) of human oocytes is a reproductive technique which has been practiced for 25 years and is gaining popularity. However, the techniques used for IVM differ substantially across clinics and they result in extremely variable pregnancy rates, partially due to some of these differences in protocols. Such differences include the use in some cycles of hCG triggering prior to oocyte retrieval and the use of a few days of gonadotrophin treatment to support moderate follicle growth. Other important factors are patient selection (including those with polycystic ovaries or decreased ovarian reserve), the number of embryos transferred and cleavage-stage embryo or blastocyst transfer. There are also substantial differences of opinion among clinicians regarding IVM and what it implies. Due to the large variation in protocols, a decision was made to write this paper in an attempt to introduce uniformity when comparing treatments and outcomes of IVM. A clinical definition of IVM was developed: The retrieval of oocytes from small and intermediate sized follicles in an ovary before the largest follicle has surpassed 13 mm in mean diameter. The use of short gonadotrophin stimulation should be acknowledged. However, it should be stated that metaphase II oocytes also have the potential to be collected at that time in the cycles associated with either hCG or GnRH agonist priming. Many feel this is not IVM because some mature oocytes are retrieved, therefore, we recommend renaming this procedure either natural cycle IVF or modified natural cycle IVF (if gonadotrophin stimulation is given) with early triggering, combined with IVM The percentage as well as the absolute number of mature oocytes at retrieval should be indicated. The use of these titles will allow transparency when comparing results of IVM cycles. [ABSTRACT FROM AUTHOR]

Study Question: Are there temporal trends of sperm concentration (SC) and total sperm count (TSC) in Chinese healthy males from 1981 to 2019?Summary Answer: Our result indicated a temporal decrease in SC and TSC among 327 373 healthy Chinese men in the recent four decades.What Is Known Already: A review of 61 papers reported a temporal decline in SC and TSC from 1938 to 1990. This trend was later confirmed by a systematic review of 185 published papers from 1981 to 2013. However, the majority of the included individuals were from western countries. In China, whether SC and TSC have declined remains controversial.Study Design, Size, Duration: This systematic review of published articles used data extracted from Pubmed, Science Direct, Embase, China-National-Knowledge-Infrastructure (CNKI) and Wanfang Data to assess changes in SC and TSC in China from 1981 to 2019.Participants/materials, Setting, Methods: A total of 111 studies including 327 373 individuals who provided semen samples from 1981 to 2019 were extracted for the present analysis. Study selection and data extraction were performed by two independent researchers. The trends in SC and TSC were analysed using liner-regression and meta-regression before and after adjusting for potential covariates. Moreover, subgroups, categorised based on geographic region, fertility status or recruitment source, were also analysed.Main Results and the Role Of Chance: SC declined significantly (slope liner-regression = -0.748 million/ml/year; P = 0.005; slope meta-regression = -0.824 million/ml/year; P < 0.001) between 1981 and 2019 in China. Trends for TSC was similar to that for SC (slope liner-regression = -2.073 million/year; P = 0.032; slope meta-regression = -2.188 million/year; P = 0.003). In subgroup meta-regression analyses, males with definite fertility had continuous declines in SC (slope northern group=-2.268, P = 0.009; slope southern group=-1.014, P = 0.009) and TSC (slope northern group=-9.675, P = 0.010; slope southern group=-3.215, P = 0.042). However, in the unselected group, where fertility status was unknown, the obvious downward trend in SC was only seen in males from Northern regions (slope = -0.836, P = 0.003). Another subgroup analysis demonstrated that obvious decreases in SC (slope = -1.432, P < 0.001) and TSC (slope=-4.315, P = 0.001) were only seen in volunteer groups but not in pre-pregnancy examination groups and other recruitment groups. The results changed minimally in multiple sensitivity analyses.Limitations, Reasons For Caution: The validity of the meta-analysis results was limited mainly by the quality of the included studies. Additionally, our study spanned many decades and the recommended criteria for some semen parameter assessments have significantly changed, which may bring about some unavoidable bias. Moreover, the data remain insufficient especially in some provinces of China.Wider Implications Of the Findings: The present study is the first study to report significant decreases in SC and TSC in 327 373 healthy Chinese men between 1981 and 2019, indicating a serious reproductive health warning. Further studies on the causes of the declines are urgently needed.Study Funding/competing Interest(s): D.Z. is supported by the National Natural Science Funding of China, Natural Science Funding of Shaanxi Province, Science Funding of Health Department, Shaanxi Province, Fundamental Research Funds for the Central University and the Project of Independent Innovative Experiment for Postgraduates in Medicine in Xi'an Jiaotong University. The authors have no conflicts of interests to declare.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

STUDY QUESTION Would the different regulatory approaches for preimplantation genetic testing (PGT) in Europe permit the implementation of preimplantation genetic testing using polygenic risk scores (PGT-P)? SUMMARY ANSWER While the regulatory approaches for PGT differ between countries, the space provided for potential implementation of PGT-P seems limited in all three regulatory models. WHAT IS KNOWN ALREADY PGT is a reproductive genetic technology that allows the testing for hereditary genetic disorders and chromosome abnormalities in embryos before implantation. Throughout its history, PGT has largely been regarded as an ethically sensitive technology. For example, ethical questions have been raised regarding the use of PGT for adult-onset conditions, non-medical sex selection, and human leukocyte antigen typing for the benefit of existing siblings. Countries in which PGT is offered each have their own approach of regulating the clinical application of PGT, and a clear overview of legal and practical regulation of PGT in Europe is lacking. An emerging development within the field of PGT, namely PGT-P, is currently bringing new ethical tensions to the forefront. It is unclear whether PGT-P may be applied within the current regulatory frameworks in Europe. Therefore, it is important to investigate current regulatory frameworks in Europe and determine whether PGT-P fits within these frameworks. STUDY DESIGN, SIZE, DURATION The aim of this study was to provide an overview of the legal and practical regulation of the use of PGT in seven selected European countries (Belgium, France, Germany, Italy, the Netherlands, Spain, and the UK) and critically analyse the different approaches with regards to regulatory possibilities for PGT-P. Between July and September 2023, we performed a thorough and extensive search of websites of governments and governmental agencies, websites of scientific and professional organizations, and academic articles in which laws and regulations are described. PARTICIPANTS/MATERIALS, SETTING, METHODS We investigated the legal and regulatory aspects of PGT by analysing legal documents, regulatory frameworks, scientific articles, and guidelines from scientific organizations and regulatory bodies to gather relevant information about each included country. The main sources of information were national laws relating to PGT. MAIN RESULTS AND THE ROLE OF CHANCE We divided the PGT regulation approaches into three models. The regulation of PGT differs per country, with some countries requiring central approval of PGT for each new indication (the medical indication model: the UK, the Netherlands), other countries evaluating each individual PGT request at the local level (the individual requests model: France, Germany), and countries largely leaving decision-making about clinical application of PGT to healthcare professionals (the clinical assessment model: Belgium, Italy, Spain). In the countries surveyed that use the medical indication model and the individual requests model, current legal frameworks and PGT criteria seem to exclude PGT-P. In countries using the clinical assessment model, the fact that healthcare professionals and scientific organizations in Europe are generally negative about implementation of PGT-P due to scientific and socio-ethical concerns, implies that, even if it were legally possible, the chance that PGT-P would be offered in the near future might be low. LIMITATIONS, REASONS FOR CAUTION The results are based on our interpretation of publicly available written information and documents, therefore not all potential discrepancies between law and practice might have been identified. In addition, our analysis focuses on seven—and not all—European countries. However, since these countries are relevant players within PGT in Europe and since they have distinct PGT regulations, the insights gathered give relevant insights into diverse ways of PGT regulation. WIDER IMPLICATIONS OF THE FINDINGS To the best of our knowledge, this is the first paper that provides a thorough overview of the legal and practical regulation of PGT in Europe. Our analysis of how PGT-P fits within current regulation models provides guidance for healthcare professionals and policymakers in navigating the possible future implementation of PGT-P within Europe. STUDY FUNDING/COMPETING INTEREST(s) This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 813707. The authors declare no conflict of interest. TRIAL REGISTRATION NUMBER N/A. [ABSTRACT FROM AUTHOR]

STUDY QUESTION Which clinical and embryological factors should be considered to apply double embryo transfer (DET) instead of elective single embryo transfer (eSET)? SUMMARY ANSWER No clinical or embryological factor per se justifies a recommendation of DET instead of eSET in IVF/ICSI. WHAT IS KNOWN ALREADY DET is correlated with a higher rate of multiple pregnancy, leading to a subsequent increase in complications for both mother and babies. These complications include preterm birth, low birthweight, and other perinatal adverse outcomes. To mitigate the risks associated with multiple pregnancy, eSET is recommended by international and national professional organizations as the preferred approach in ART. STUDY DESIGN, SIZE, DURATION The guideline was developed according to the structured methodology for development and update of ESHRE guidelines. Literature searches were performed in PUBMED/MEDLINE and Cochrane databases, and relevant papers published up to May 2023, written in English, were included. Live birth rate, cumulative live birth rate, and multiple pregnancy rate were considered as critical outcomes. PARTICIPANTS/MATERIALS, SETTING, METHODS Based on the collected evidence, recommendations were discussed until a consensus was reached within the Guideline Development Group (GDG). A stakeholder review was organized after the guideline draft was finalized. The final version was approved by the GDG and the ESHRE Executive Committee. MAIN RESULTS AND THE ROLE OF CHANCE The guideline provides 35 recommendations on the medical and non-medical risks associated with multiple pregnancies and on the clinical and embryological factors to be considered when deciding on the number of embryos to transfer. These recommendations include 25 evidence-based recommendations, of which 24 were formulated as strong recommendations and one as conditional, and 10 good practice points. Of the evidence-based recommendations, seven (28%) were supported by moderate-quality evidence. The remaining recommendations were supported by low (three recommendations; 12%), or very low-quality evidence (15 recommendations; 60%). Owing to the lack of evidence-based research, the guideline also clearly mentions recommendations for future studies. LIMITATIONS, REASONS FOR CAUTION The guideline assessed different factors one by one based on existing evidence. However, in real life, clinicians' decisions are based on several prognostic factors related to each patient's case. Furthermore, the evidence from randomized controlled trials is too scarce to formulate high-quality evidence-based recommendations. WIDER IMPLICATIONS OF THE FINDINGS The guideline provides health professionals with clear advice on best practice in the decision-making process during IVF/ICSI, based on the best evidence currently available, and recommendations on relevant information that should be communicated to patients. In addition, a list of research recommendations is provided to stimulate further studies in the field. STUDY FUNDING/COMPETING INTEREST(S) The guideline was developed and funded by ESHRE, covering expenses associated with the guideline meetings, the literature searches, and the dissemination of the guideline. The guideline group members did not receive payment. DPB declared receiving honoraria for lectures from Merck, Ferring, and Gedeon Richter. She is a member of ESHRE EXCO, and the Mediterranean Society for reproductive medicine and the president of the Croatian Society for Gynaecological Endocrinology and Reproductive Medicine. CDG is the past Chair of the ESHRE EIM Consortium and a paid deputy member of the Editorial board of Human Reproduction. IR declared receiving reimbursement from ESHRE and EDCD for attending meetings. She holds an unpaid leadership role in OBBCSSR, ECDC Sohonet, and AER. KAR-W declared receiving grants for clinical researchers and funding provision to the institution from the Swedish Cancer Society (200170F), the Senior Clinical Investigator Award, Radiumhemmets Forskningsfonder (Dnr: 201313), Stockholm County Council FoU (FoUI-953912) and Karolinska Institutet (Dnr 2020-01963), NovoNordisk, Merck and Ferring Pharmaceuticals. She received consulting fees from the Swedish Ministry of Health and Welfare. She received honoraria from Roche, Pfizer, and Organon for chairmanship and lectures. She received support from Organon for attending meetings. She participated in advisory boards for Merck, Nordic countries, and Ferring. She declared receiving time-lapse equipment and grants with payment to institution for pre-clinical research from Merck pharmaceuticals and from Ferring. SS-R received research funding from Roche Diagnostics, Organon/MSD, Theramex, and Gedeo-Richter. He received consulting fees from Organon/MSD, Ferring Pharmaceuticals, and Merck Serono. He declared receiving honoraria for lectures from Ferring Pharmaceuticals, Besins, Organon/MSD, Theramex, and Gedeon Richter. He received support for attending Gedeon Richter meetings and participated in the Data Safety Monitoring Board of the T-TRANSPORT trial. He is the Deputy of ESHRE SQART special interest group. He holds stock options in IVI Lisboa and received equipment and other services from Roche Diagnostics and Ferring Pharmaceuticals. KT declared receiving payment for honoraria for giving lectures from Merck Serono and Organon. She is member of the safety advisory board of EDQM. She holds a leadership role in the ICCBBA board of directors. ZV received reimbursement from ESHRE for attending meetings. She also received research grants from ESHRE and Juhani Aaltonen Foundation. She is the coordinator of EHSRE SQART special interest group. The other authors have no conflicts of interest to declare. DISCLAIMER This guideline represents the views of ESHRE, which were achieved after careful consideration of the scientific evidence available at the time of preparation. In the absence of scientific evidence on certain aspects, a consensus between the relevant ESHRE stakeholders has been obtained. Adherence to these clinical practice guidelines does not guarantee a successful or specific outcome, nor does it establish a standard of care. Clinical practice guidelines do not replace the need for application of clinical judgement to each individual presentation, nor variations based on locality and facility type. ESHRE makes no warranty, express or implied, regarding the clinical practice guidelines and specifically excludes any warranties of merchantability and fitness for a particular use or purpose (full disclaimer available at https://www.eshre.eu/Guidelines-and-Legal). [ABSTRACT FROM AUTHOR]

STUDY QUESTION What were the frequency and temporal trends of reporting P -values and effect measures in the abstracts of reproductive medicine studies in 1990–2022, how were reported P -values distributed, and what proportion of articles that present with statistical inference reported statistically significant results, i.e. 'positive' results? SUMMARY ANSWER Around one in six abstracts reported P -values alone without effect measures, while the prevalence of effect measures, whether reported alone or accompanied by P -values, has been increasing, especially in meta-analyses and randomized controlled trials (RCTs); the reported P -values were frequently observed around certain cut-off values, notably at 0.001, 0.01, or 0.05, and among abstracts present with statistical inference (i.e. P -value, CIs, or significant terms), a large majority (77%) reported at least one statistically significant finding. WHAT IS KNOWN ALREADY Publishing or reporting only results that show a 'positive' finding causes bias in evaluating interventions and risk factors and may incur adverse health outcomes for patients.   Despite efforts to minimize publication reporting bias in medical research, it remains unclear whether the magnitude and patterns of the bias have changed over time. STUDY DESIGN, SIZE, DURATION We studied abstracts of reproductive medicine studies from 1990 to 2022. The reproductive medicine studies were published in 23 first-quartile journals under the category of Obstetrics and Gynaecology and Reproductive Biology in Journal Citation Reports and 5 high-impact general medical journals (The Journal of the American Medical Association , The Lancet , The BMJ , The New England Journal of Medicine , and PLoS Medicine). Articles without abstracts, animal studies, and non-research articles, such as case reports or guidelines, were excluded. PARTICIPANTS/MATERIALS, SETTING, METHODS Automated text-mining was used to extract three types of statistical significance reporting, including P -values, CIs, and text description. Meanwhile, abstracts were text-mined for the presence of effect size metrics and Bayes factors. Five hundred abstracts were randomly selected and manually checked for the accuracy of automatic text extraction. The extracted statistical significance information was then analysed for temporal trends and distribution in general as well as in subgroups of study designs and journals. MAIN RESULTS AND THE ROLE OF CHANCE A total of 24 907 eligible reproductive medicine articles were identified from 170 739 screened articles published in 28 journals. The proportion of abstracts not reporting any statistical significance inference halved from 81% (95% CI, 76–84%) in 1990 to 40% (95% CI, 38–44%) in 2021, while reporting P -values alone remained relatively stable, at 15% (95% CI, 12–18%) in 1990 and 19% (95% CI, 16–22%) in 2021. By contrast, the proportion of abstracts reporting effect measures alone increased considerably from 4.1% (95% CI, 2.6–6.3%) in 1990 to 26% (95% CI, 23–29%) in 2021. Similarly, the proportion of abstracts reporting effect measures together with P -values showed substantial growth from 0.8% (95% CI, 0.3–2.2%) to 14% (95% CI, 12–17%) during the same timeframe. Of 30 182 statistical significance inferences, 56% (n = 17 077) conveyed statistical inferences via P -values alone, 30% (n = 8945) via text description alone such as significant or non-significant, 9.3% (n = 2820) via CIs alone, and 4.7% (n = 1340) via both CI and P -values. The reported P -values (n = 18 417), including both a continuum of P -values and dichotomized P -values, were frequently observed around common cut-off values such as 0.001 (20%), 0.05 (16%), and 0.01 (10%). Of the 13 200 reproductive medicine abstracts containing at least one statistical inference, 77% of abstracts made at least one statistically significant statement. Among articles that reported statistical inference, a decline in the proportion of making at least one statistically significant inference was only seen in RCTs, dropping from 71% (95% CI, 48–88%) in 1990 to 59% (95% CI, 42–73%) in 2021, whereas the proportion in the rest of study types remained almost constant over the years. Of abstracts that reported P -value, 87% (95% CI, 86–88%) reported at least one statistically significant P -value; it was 92% (95% CI, 82–97%) in 1990 and reached its peak at 97% (95% CI, 93–99%) in 2001 before declining to 81% (95% CI, 76–85%) in 2021. LIMITATIONS, REASONS FOR CAUTION First, our analysis focused solely on reporting patterns in abstracts but not full-text papers; however, in principle, abstracts should include condensed impartial information and avoid selective reporting. Second, while we attempted to identify all types of statistical significance reporting, our text mining was not flawless. However, the manual assessment showed that inaccuracies were not frequent. WIDER IMPLICATIONS OF THE FINDINGS There is a welcome trend that effect measures are increasingly reported in the abstracts of reproductive medicine studies, specifically in RCTs and meta-analyses. Publication reporting bias remains a major concern. Inflated estimates of interventions and risk factors could harm decisions built upon biased evidence, including clinical recommendations and planning of future research. STUDY FUNDING/COMPETING INTEREST(S) No funding was received for this study. B.W.M. is supported by an NHMRC Investigator grant (GNT1176437); B.W.M. reports research grants and travel support from Merck and consultancy from Merch and ObsEva. W.L. is supported by an NHMRC Investigator Grant (GNT2016729). Q.F. reports receiving a PhD scholarship from Merck. The other author has no conflict of interest to declare. TRIAL REGISTRATION NUMBER N/A. [ABSTRACT FROM AUTHOR]

Study Question: Do distinct subpopulations of decidual stromal cells (DSCs) exist and if so, are given subpopulations enriched in recurrent miscarriage (RM)?Summary Answer: Three subpopulations of DSCs were identified from which inflammatory DSCs (iDSCs) and glycolytic DSCs (glyDSCs) are significantly enriched in RM, with implicated roles in driving decidual inflammation and immune dysregulation.What Is Known Already: DSCs play crucial roles in establishing and maintaining a successful pregnancy; dysfunction of DSCs has been considered as one of the key reasons for the development of RM.Study Design, Size, Duration: We collected 15 early decidual samples from five healthy donors (HDs) and ten RM patients to perform single-cell RNA sequencing (scRNA-seq). A total of 43 RM patients and 37 HDs were enrolled in the validation cohort.Participants/materials, Setting, Methods: Non-immune cells and immune cells of decidual tissues were sorted by flow cytometry to perform scRNA-seq. We used tissue microarrays (TMA) to validate three distinct subpopulations of DSCs. The expression of inflammatory and glycolytic proteins by DSCs was validated by immunohistochemistry (IHC) and multiplex immunohistochemistry (mIHC). Different subsets of decidual NK (dNK) cells and macrophages were also validated by multicolor flow cytometry and mIHC. Cell ligand-receptor and spatial analyses between DSCs and immune cells were analyzed by mIHC.Main Results and the Role Of Chance: We classify the DSCs into three subtypes based on scRNA-seq data: myofibroblastic (myDSCs), inflammatory (iDSCs) and glycolytic (glyDSCs), with the latter two being significantly enriched in RM patients. The distribution patterns of DSC subtypes in the RM and HD groups were validated by mIHC. Single-cell analyses indicate that the differentiation of iDSCs and glyDSCs may be coupled with the degrees of hypoxia. Consequently, we propose a pathological model in which a vicious circle is formed and fueled by hypoxic stress, uncontrolled inflammation and aberrant glycolysis. Furthermore, our results show that the inflammatory SPP1+ macrophages and CD18+ dNK cells are preferentially increased in the decidua of RM patients. Cell ligand-receptor and mIHC spatial analyses uncovered close interactions between pathogenic DSCs and inflammatory SPP1+ macrophages and CD18+ NK cells in RM patients.Large Scale Data: The raw single-cell sequence data reported in this paper were deposited at the National Omics Data Encyclopedia (www.biosino.org), under the accession number OEP002901.Limitations, Reasons For Caution: The number of decidual samples for scRNA-seq was limited and in-depth functional studies on DSCs are warranted in future studies.Wider Implications Of the Findings: Identification of three DSC subpopulations opens new avenues for further investigation of their roles in RM patients.Study Funding/competing Interest(s): This study was supported by the Strategic Priority Research Program (No. XDB29030302), Frontier Science Key Research Project (QYZDB-SSW-SMC036), Chinese Academy of Sciences; National Key Research and Development Program of China (2021YFE0200600), National Natural Science Foundation of China (No. 31770960), Shanghai Municipal Science and Technology Major Project (No. 2019SHZDZX02, HS2021SHZX001), and Shanghai Committee of Science and Technology (17411967800). All authors report no conflict of interest. [ABSTRACT FROM AUTHOR]

STUDY QUESTION To what extent is preconception maternal or paternal coronavirus disease 2019 (COVID-19) vaccination associated with miscarriage incidence? SUMMARY ANSWER COVID-19 vaccination in either partner at any time before conception is not associated with an increased rate of miscarriage. WHAT IS KNOWN ALREADY Several observational studies have evaluated the safety of COVID-19 vaccination during pregnancy and found no association with miscarriage, though no study prospectively evaluated the risk of early miscarriage (gestational weeks [GW] <8) in relation to COVID-19 vaccination. Moreover, no study has evaluated the role of preconception vaccination in both male and female partners. STUDY DESIGN, SIZE, DURATION An Internet-based, prospective preconception cohort study of couples residing in the USA and Canada. We analyzed data from 1815 female participants who conceived during December 2020–November 2022, including 1570 couples with data on male partner vaccination. PARTICIPANTS/MATERIALS, SETTING, METHODS Eligible female participants were aged 21–45 years and were trying to conceive without use of fertility treatment at enrollment. Female participants completed questionnaires at baseline, every 8 weeks until pregnancy, and during early and late pregnancy; they could also invite their male partners to complete a baseline questionnaire. We collected data on COVID-19 vaccination (brand and date of doses), history of SARS-CoV-2 infection (yes/no and date of positive test), potential confounders (demographic, reproductive, and lifestyle characteristics), and pregnancy status on all questionnaires. Vaccination status was categorized as never (0 doses before conception), ever (≥1 dose before conception), having a full primary sequence before conception, and completing the full primary sequence ≤3 months before conception. These categories were not mutually exclusive. Participants were followed up from their first positive pregnancy test until miscarriage or a censoring event (induced abortion, ectopic pregnancy, loss to follow-up, 20 weeks' gestation), whichever occurred first. We estimated incidence rate ratios (IRRs) for miscarriage and corresponding 95% CIs using Cox proportional hazards models with GW as the time scale. We used propensity score fine stratification weights to adjust for confounding. MAIN RESULTS AND THE ROLE OF CHANCE Among 1815 eligible female participants, 75% had received at least one dose of a COVID-19 vaccine by the time of conception. Almost one-quarter of pregnancies resulted in miscarriage, and 75% of miscarriages occurred <8 weeks' gestation. The propensity score-weighted IRR comparing female participants who received at least one dose any time before conception versus those who had not been vaccinated was 0.85 (95% CI: 0.63, 1.14). COVID-19 vaccination was not associated with increased risk of either early miscarriage (GW: <8) or late miscarriage (GW: 8–19). There was no indication of an increased risk of miscarriage associated with male partner vaccination (IRR = 0.90; 95% CI: 0.56, 1.44). LIMITATIONS, REASONS FOR CAUTION The present study relied on self-reported vaccination status and infection history. Thus, there may be some non-differential misclassification of exposure status. While misclassification of miscarriage is also possible, the preconception cohort design and high prevalence of home pregnancy testing in this cohort reduced the potential for under-ascertainment of miscarriage. As in all observational studies, residual or unmeasured confounding is possible. WIDER IMPLICATIONS OF THE FINDINGS This is the first study to evaluate prospectively the relation between preconception COVID-19 vaccination in both partners and miscarriage, with more complete ascertainment of early miscarriages than earlier studies of vaccination. The findings are informative for individuals planning a pregnancy and their healthcare providers. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the National Institute of Health [R01-HD086742 (PI: L.A.W.); R01-HD105863S1 (PI: L.A.W. and M.L.E.)], the National Institute of Allergy and Infectious Diseases (R03-AI154544; PI: A.K.R.), and the National Science Foundation (NSF-1914792; PI: L.A.W.). The funders had no role in the study design, data collection, analysis and interpretation of data, writing of the report, or the decision to submit the paper for publication. L.A.W. is a fibroid consultant for AbbVie, Inc. She also receives in-kind donations from Swiss Precision Diagnostics (Clearblue home pregnancy tests) and Kindara.com (fertility apps). M.L.E. received consulting fees from Ro, Hannah, Dadi, VSeat, and Underdog, holds stock in Ro, Hannah, Dadi, and Underdog, is a past president of SSMR, and is a board member of SMRU. K.F.H. reports being an investigator on grants to her institution from UCB and Takeda, unrelated to this study. S.H.-D. reports being an investigator on grants to her institution from Takeda, unrelated to this study, and a methods consultant for UCB and Roche for unrelated drugs. The authors report no other relationships or activities that could appear to have influenced the submitted work. TRIAL REGISTRATION NUMBER N/A. [ABSTRACT FROM AUTHOR]

Study Question: Which essential items should be recorded before, during and after endometriosis surgery and in clinical outcome based surgical trials in patients with deep endometriosis (DE)?Summary Answer: A DE surgical sheet (DESS) was developed for standardized reporting of the surgical treatment of DE and an international expert consensus proposal on relevant items that should be recorded in surgical outcome trials in women with DE.What Is Known Already: Surgery is an important treatment for symptomatic DE. So far, data have been reported in such a way that comparison of different surgical techniques is impossible. Therefore, we present an international expert proposal for standardized reporting of surgical treatment and surgical outcome trials in women with DE.Study Design, Size, Duration: International expert consensus based on a systematic review of literature.Participants/materials, Setting, Methods: Taking into account recommendations from Consolidated Standards of Reporting Trials (CONSORT), the Innovation Development Exploration Assessment and Long-term Study (IDEAL), the Initiative on Methods, Measurement and Pain Assessment in Clinical trials (IMMPACT) and the World Endometriosis Research Foundation Phenome and Biobanking Harmonisation Project (WERF EPHect), a systematic literature review on surgical treatment of DE was performed and resulted in a proposal for standardized reporting, adapted by contributions from eight members of the multidisciplinary Leuven University Hospitals Endometriosis Care Program, from 18 international experts and from audience feedback during three international meetings.Main Results and the Role Of Chance: We have developed the DESS to record in detail the surgical procedures for DE, and an international consensus on pre-, intra- and post-operative data that should be recorded in surgical outcome trials on DE.Limitations, Reasons For Caution: The recommendations in this paper represent a consensus among international experts based on a systematic review of the literature. For several items and recommendations, high-quality RCTs were not available. Further research is needed to validate and evaluate the recommendations presented here.Wider Implications Of the Findings: This international expert consensus for standardized reporting of surgical treatment in women with DE, based on a systematic literature review and international consensus, can be used as a guideline to record and report surgical management of patients with DE and as a guideline to design, execute, interpret and compare clinical trials in this patient population.Study Funding/competing Interests: None of the authors received funding for the development of this paper. M.A. reports personal fees and non-financial support from Bayer Pharma outside the submitted work; H.T. reports a grant from Pfizer and personal fees for being on the advisory board of Perrigo, Abbvie, Allergan and SPD.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

The pharmaceutical and device industry has greatly contributed to diagnostic and therapeutic approaches in reproductive medicine in a very highly regulated environment, ensuring that development and manufacturing follow the highest standards. In spite of these achievements, collaboration between industry and physicians/academia is often presented in a negative context. However, today more than ever, partnership between industry and academia is needed to shorten the timeline between innovation and application, and to achieve faster access to better diagnostics, drugs and devices for the benefit of patients and society, based on complementary knowledge, skills and expertise. Such partnerships can include joined preclinical/clinical and post-marketing research and development, joint intellectual property, and joint revenue. In Europe, the transparency of this collaboration between pharmaceutical industry and medical doctors has been made possible by the Compliance and Disclosure Policy published by the European Federation of Pharmaceutical Industries and Associations (EFPIA), which represents the major pharmaceutical companies operating in Europe, and includes as members some but not all companies active in infertility and women's health. Under the EFPIA Disclosure Code of conduct, companies need to disclose transfers of value including amounts, activity type and the names of the recipient Health Care Professionals and Organizations. EFPIA member companies have also implemented very strict internal quality control processes and procedures in the design, statistical analysis, reporting, publication and communication of clinical research, according to Good Clinical Practice and other regulations, and are regularly inspected by competent authorities such as the US Food and Drug Administration (FDA) or European Medicines Agency (EMA) for all trials used in marketing authorization applications. The risk of scientific bias exists not only in the pharmaceutical industry but also in the academic world. When academics believe in a hypothesis, they may build their case by emphasizing the arguments supporting their case, and either refute, refuse, oppose or ignore arguments that challenge their assumptions. A possible solution to reduce this bias is international consensus on study design, data collection, statistical analysis and reporting of outcomes, especially in the area of personalized reproductive medicine, e.g. to demonstrate superiority or non-inferiority of personalized ovarian stimulation using biomarkers. Equally important is that declarations of interest are reported transparently and completely in scientific abstracts and publications, and that ghost authorship is replaced by proactive and clear co-authorship for experts from industry where such co-authorship is required based on the prevailing ICMJE criteria. In that context, however, reviewers should stop believing that publications by industry authors only, or by mixed groups of co-authors from industry and academia, are more prone to bias than papers from academic groups only. Instead, the scientific quality of the work should be the only relevant criterion for acceptance of papers or abstracts, regardless of the environment where the work was done. In the end, neutrality does not exist and different beliefs and biases exist within and between healthcare professionals and organizations and pharmaceutical industries. The challenge is to be transparent about this reality at all times, and to behave in an informed, balanced and ethical way as medical and scientific experts, taking into account compliance and legal regulations of both industry and academic employers, in the best interest of patients and society. [ABSTRACT FROM AUTHOR]

Study Question: Do polymorphisms in the anti-Müllerian hormone (AMH) promoter have an effect on AMH levels in patients with polycystic ovary syndrome (PCOS)?Summary Answer: We have identified a novel AMH promoter polymorphism rs10406324 that is associated with lower serum AMH levels and is suggested to play a role in the mechanism of regulation of AMH gene expression in women.What Is Known Already: Follicle number is positively correlated with serum AMH levels, reflected by elevated AMH levels in women with PCOS. In addition, it is suggested that AMH production per follicle is higher in women with PCOS than in normo-ovulatory women, implying an altered regulation of AMH in PCOS.Study Design, Size, Duration: A discovery cohort of 655 PCOS women of Northern European ancestry and both an internal and external validation PCOS cohort (n = 458 and n = 321, respectively) were included in this study. Summary-level data of an AMH genome-wide association study meta-analysis including 7049 normo-ovulatory women was included as a control cohort. A genetic approach was taken through association analysis and in silico analysis of the associated variants in the AMH promoter. In vitro analysis was performed to investigate the functional mechanisms.Participants/materials, Setting, Methods: All common two-allelic single-nucleotide polymorphisms (SNPs) in the region Chr19:2 245 353-2 250 827 bp (Build 37) were selected for the analysis. Linear regression analyses were performed to determine the association between SNPs in the AMH promoter region and serum AMH levels. For the in silico analysis, the webtools 'HaploReg' v4.1 for ENCODE prediction weight matrices and 'atSNP' were used. In vitro analysis was performed using KK1 cells, a mouse granulosa cell line and COV434 cells, a human granulosa tumor cell line. Cells were transfected with the reference or the variant human AMH promoter reporter construct together with several transcription factors (TFs). Dual-Glo® Luciferase Assay was performed to measure the luciferase activity.Main Results and the Role Of Chance: Polymorphism rs10406324 was significantly associated with serum AMH levels in all three PCOS cohorts. Carriers of the minor allele G had significantly lower log-transformed serum AMH levels compared to non-carriers (P = 8.58 × 10-8, P = 1.35 × 10-3 and P = 1.24 × 10-3, respectively). This result was validated in a subsequent meta-analysis (P = 3.24 × 10-12). Interestingly, rs10406324 was not associated with follicle count, nor with other clinical traits. Also, in normo-ovulatory women, the minor allele of this variant was associated with lower serum AMH levels (P = 1.04 × 10-5). These findings suggest that polymorphism rs10406324 plays a role in the regulation of AMH expression, irrespective of clinical background. In silico analysis suggested a decreased binding affinity of the TFs steroidogenenic factor 1, estrogen-related receptor alpha and glucocorticoid receptor to the minor allele G variant, however in vitro analysis did not show a difference in promoter activity between the A and G allele.Limitations, Reasons For Caution: Functional analyses were performed in a mouse and a human granulosa cell line using an AMH promoter reporter construct. This may have limited assessment of the impact of the polymorphism on higher order chromatin structures. Human granulosa cells generated from induced pluripotent stem cells, combined with gene editing, may provide a method to elucidate the exact mechanism behind the decrease in serum AMH levels in carriers of the -210 G allele. We acknowledge that the lack of follicle number in the external validation and the control cohort is a limitation of the paper. Although we observed that the association between rs10406324 and AMH levels was independent of follicle number in our discovery and internal validation PCOS cohorts, we cannot fully rule out that the observed effects on serum AMH levels are, in part, caused by differences in follicle number.Wider Implications Of the Findings: These results suggest that variations in serum AMH levels are not only caused by differences in follicle number but also by genetic factors. Therefore, the genetic context should be taken into consideration when assessing serum AMH levels in women. This may have clinical consequences when serum AMH levels are used as a marker for the polycystic ovarian morphology phenotype.Study Funding/competing Interest(s): No external funding was used. J.S.E.L. has received consultancy fees from the following companies: Ferring, Roche Diagnostics and Ansh Labs and has received travel reimbursement from Ferring. J.A.V. has received royalties from AMH assays, paid to the institute/lab with no personal financial gain. The other authors declare no competing interests.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

Ulipristal acetate (UPA) is a medical treatment for uterine fibroids and was authorized for surgical pre-treatment in 2012 after the conduct of the PEARL I and II randomized controlled trials and for intermittent treatment after the observational PEARL III and IV trials. However, UPA came into disrepute due to its temporary suspension in 2017 and 2020 because of an apparent association with liver injury. This clinical opinion paper aims to review the process of marketing authorization and implementation of UPA, in order to provide all involved stakeholders with recommendations for the introduction of future drugs. Before marketing authorization, the European Medicines Agency (EMA) states that Phase III registration trials should evaluate relevant outcomes in a representative population, while comparing to gold-standard treatment. This review shows that the representativeness of the study populations in all PEARL trials was limited, surgical outcomes were not evaluated and intermittent treatment was assessed without comparative groups. Implementation into clinical practice was extensive, with 900 000 prescribed treatment cycles in 5 years in Europe and Canada combined. Extremely high costs are involved in developing and evaluating pre-marketing studies in new drugs, influencing trial design and relevance of chosen outcomes, thereby impeding clinical applicability. It is vitally important that the marketing implementation after authorization is regulated in such way that necessary evidence is generated before widespread prescription of a new drug. All stakeholders, from pharmaceutical companies to authorizing bodies, governmental funding bodies and medical professionals should be aware of their role and take responsibility for their part in this process. [ABSTRACT FROM AUTHOR]

Study Question: What is the likelihood of having a child within 4 years for men and women with strong short-term reproductive intentions, and how is it affected by age?Summary Answer: For women, the likelihood of realising reproductive intentions decreased steeply from age 35: the effect of age was weak and not significant for men.What Is Known Already: Men and women are postponing childbearing until later ages. For women, this trend is associated with a higher risk that childbearing plans will not be realised due to increased levels of infertility and pregnancy complications.Study Design, Size, Duration: This study analyses two waves of the nationally representative Household, Income and Labour Dynamics in Australia (HILDA) survey. The analytical sample interviewed in 2011 included 447 men aged 18-45 and 528 women aged 18-41. These respondents expressed a strong intention to have a child in the next 3 years. We followed them up in 2015 to track whether their reproductive intention was achieved or revised.Participants/materials, Settings, Methods: Multinomial logistic regression is used to account for the three possible outcomes: (i) having a child, (ii) not having a child but still intending to have one in the future and (iii) not having a child and no longer intending to have one. We analyse how age, parity, partnership status, education, perceived ability to conceive, self-rated health, BMI and smoking status are related to realising or changing reproductive intentions.Main Results and the Role Of Chance: Almost two-thirds of men and women realised their strong short-term fertility plans within 4 years. There was a steep age-related decline in realising reproductive intentions for women in their mid- and late-30s, whereas men maintained a relatively high probability of having the child they intended until age 45. Women aged 38-41 who planned to have a child were the most likely to change their plan within 4 years. The probability of realising reproductive intention was highest for married and highly educated men and women and for those with one child.Limitations, Reasons For Caution: Our study cannot separate biological, social and cultural reasons for not realising reproductive intentions. Men and women adjust their intentions in response to their actual circumstances, but also in line with their perceived ability to have a child or under the influence of broader social norms on reproductive age.Wider Implications Of the Findings: Our results give a new perspective on the ability of men and women to realise their reproductive plans in the context of childbearing postponement. They confirm the inequality in the individual consequences of delayed reproduction between men and women. They inform medical practitioners and counsellors about the complex biological, social and normative barriers to reproduction among women at higher childbearing ages.Study Funding/competing Interest(s): This research was partly supported by a Research School of Social Sciences Visiting Fellowship at the Australian National University and an Australian Research Council Discovery Project (DP150104248). Éva Beaujouan's work was partly funded by the Austrian Science Fund (FWF) project 'Later Fertility in Europe' (Grant agreement no. P31171-G29). This paper uses unit record data from the HILDA Survey. The HILDA Project was initiated and is funded by the Australian Government Department of Social Services (DSS) and is managed by the Melbourne Institute of Applied Economic and Social Research (Melbourne Institute). The findings and views reported in this paper, however, are those of the authors and should not be attributed to either DSS or the Melbourne Institute. The authors have no conflicts of interest. [ABSTRACT FROM AUTHOR]

STUDY QUESTION Is Mycoplasma genitalium -infection associated with reduced fecundability? SUMMARY ANSWER Preconception M. genitalium -infection was associated with 27% lower fecundability though confidence intervals were wide, and the association between M. genitalium and fecundability may be dependent on concurrent bacterial vaginosis (BV). WHAT IS KNOWN ALREADY M. genitalium has been associated with cervicitis, pelvic inflammatory disease, infertility, and preterm birth, but the extent to which M. genitalium is causally related to adverse reproductive sequelae in women is debated. STUDY DESIGN, SIZE, DURATION Kenyan women enrolled in a prospective preconception cohort provided vaginal fluid specimens and underwent monthly pregnancy testing. Stored samples from 407 women who had been trying to conceive for ≤6 months were tested for M. genitalium using a nucleic acid amplification test. PARTICIPANTS/MATERIALS, SETTING, METHODS Data on first day of last menstrual period, sexual behavior, pregnancy status, and vaginal specimens were collected at monthly preconception visits. The association between M. genitalium detected at the visit prior to each pregnancy test and fecundability was estimated using discrete time proportional probabilities models. Secondary analyses explored the influence of concurrent BV on the association between M. genitalium and fecundability. MAIN RESULTS AND THE ROLE OF CHANCE The 407 participants experienced 1220 menstrual cycles and 213 pregnancies. The prevalence of M. genitalium at enrollment was 7.7%. After adjustment for age, frequency of condomless sex in the last 4 weeks, and study site, M. genitalium was associated with a 27% lower fecundability, but confidence intervals were wide (adjusted fecundability ratio (aFR) 0.73, 95% CI 0.44, 1.23). In secondary analyses, when compared to cycles without M. genitalium or BV at the visit prior, women with both M. genitalium and BV at the visit prior had a 51% lower fecundability (aFR = 0.49, 95% CI 0.22, 1.09) whereas there was no association of M. genitalium alone (aFR = 0.98 (95% CI 0.54, 1.76)), and a smaller reduction in fecundability for women with BV only (aFR = 0.80 (95% CI 0.60, 1.07)). LIMITATIONS, REASONS FOR CAUTION Results should be interpreted cautiously given the relatively low prevalence of M. genitalium and wide confidence intervals. WIDER IMPLICATIONS OF THE FINDINGS In this cohort of Kenyan women trying to conceive, the association between M. genitalium and fecundability was influenced by concurrent BV status, suggesting there may be a synergistic effect of M. genitalium and BV on fecundability. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by a National Institutes of Health grant (NICHD R01 HD087346-RSM). R.S.M. received additional support for mentoring (NICHD K24 HD88229). E.M.L. was supported by pre- and post-doctoral fellowships (NIAID T32 AI07140, NICHD F32 HD100202). Data collection and management were completed using REDCap electronic data capture tools hosted at the University of Washington's Institute of Translational Health Science supported by grants from NCATS/NIH (UL1 TR002319). The content of this paper is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. R.S.M. receives research funding, paid to the University of Washington, from Hologic Corporation and consulting fees from Lupin Pharmaceuticals. L.E.M. receives research funding and material for research studies, paid to the University of Washington, from Hologic Corporation and Nabriva Therapeutics, travel support from Hologic, and consulting fees from Health Advances. E.M.L.'s contributions to this study primarily occurred while affiliated with the University of Washington; at the time of submission, E.M.L. was an employee of and holds stock or stock grants for AbbVie, Inc. The other authors have no conflicts of interest. TRIAL REGISTRATION NUMBER N/A. [ABSTRACT FROM AUTHOR]

STUDY QUESTION What is the recommended management for couples presenting with unexplained infertility (UI), based on the best available evidence in the literature? SUMMARY ANSWER The evidence-based guideline on UI makes 52 recommendations on the definition, diagnosis, and treatment of UI. WHAT IS KNOWN ALREADY UI is diagnosed in the absence of any abnormalities of the female and male reproductive systems after 'standard' investigations. However, a consensual standardization of the diagnostic work-up is still lacking. The management of UI is traditionally empirical. The efficacy, safety, costs, and risks of treatment options have not been subjected to robust evaluation. STUDY DESIGN, SIZE, DURATION The guideline was developed according to the structured methodology for ESHRE guidelines. Following formulation of key questions by a group of experts, literature searches, and assessments were undertaken. Papers written in English and published up to 24 October 2022 were evaluated. PARTICIPANTS/MATERIALS, SETTING, METHODS Based on the available evidence, recommendations were formulated and discussed until consensus was reached within the guideline development group (GDG). Following stakeholder review of an initial draft, the final version was approved by the GDG and the ESHRE Executive Committee. MAIN RESULTS AND THE ROLE OF CHANCE This guideline aims to help clinicians provide the best care for couples with UI. As UI is a diagnosis of exclusion, the guideline outlined the basic diagnostic procedures that couples should/could undergo during an infertility work-up, and explored the need for additional tests. The first-line treatment for couples with UI was deemed to be IUI in combination with ovarian stimulation. The place of additional and alternative options for treatment of UI was also evaluated. The GDG made 52 recommendations on diagnosis and treatment for couples with UI. The GDG formulated 40 evidence-based recommendations—of which 29 were formulated as strong recommendations and 11 as weak—10 good practice points and two research only recommendations. Of the evidence-based recommendations, none were supported by high-quality evidence, one by moderate-quality evidence, nine by low-quality evidence, and 31 by very low-quality evidence. To support future research in UI, a list of research recommendations was provided. LIMITATIONS, REASONS FOR CAUTION Most additional diagnostic tests and interventions in couples with UI have not been subjected to robust evaluation. For a large proportion of these tests and treatments, evidence was very limited and of very low quality. More evidence is required, and the results of future studies may result in the current recommendations being revised. WIDER IMPLICATIONS OF THE FINDINGS The guideline provides clinicians with clear advice on best practice in the care of couples with UI, based on the best evidence currently available. In addition, a list of research recommendations is provided to stimulate further studies in the field. The full guideline and a patient leaflet are available in www.eshre.eu/guideline/UI. STUDY FUNDING/COMPETING INTEREST(S) The guideline was developed by ESHRE, who funded the guideline meetings, literature searches, and dissemination of the guideline in collaboration with the Monash University led Australian NHMRC Centre of Research Excellence in Women's Health in Reproductive Life (CREWHIRL). The guideline group members did not receive any financial incentives; all work was provided voluntarily. D.R. reports honoraria from IBSA and Novo Nordisk. B.A. reports speakers' fees from Merck, Gedeon Richter, Organon and Intas Pharma; is part of the advisory board for Organon Turkey and president of the Turkish Society of Reproductive Medicine. S.B. reports speakers' fees from Merck, Organon, Ferring, the Ostetric and Gynaecological Society of Singapore and the Taiwanese Society for Reproductive Medicine; editor and contributing author, Reproductive Medicine for the MRCOG, Cambridge University Press; is part of the METAFOR and CAPE trials data monitoring committee. E.B. reports research grants from Roche diagnostics, Gedeon Richter and IBSA; speaker's fees from Merck, Ferring, MSD, Roche Diagnostics, Gedeon Richter, IBSA; E.B. is also a part of an Advisory Board of Ferring Pharmaceuticals, MSD, Roche Diagnostics, IBSA, Merck, Abbott and Gedeon Richter. M.M. reports consulting fees from Mojo Fertility Ltd. R.J.N. reports research grant from Australian National Health and Medical Research Council (NHMRC); consulting fees from Flinders Fertility Adelaide, VinMec Hospital Hanoi Vietnam; speaker's fees from Merck Australia, Cadilla Pharma India, Ferring Australia; chair clinical advisory committee Westmead Fertility and research institute MyDuc Hospital Vietnam. T.P. is a part of the Research Council of Finland and reports research grants from Roche Diagnostics, Novo Nordics and Sigrid Juselius foundation; consulting fees from Roche Diagnostics and organon; speaker's fees from Gedeon Richter, Roche, Exeltis, Organon, Ferring and Korento patient organization; is a part of NFOG, AE-PCOS society and several Finnish associations. S.S.R. reports research grants from Roche Diagnostics, Organon, Theramex; consulting fees from Ferring Pharmaceuticals, MSD and Organon; speaker's fees from Ferring Pharmaceuticals, MSD/Organon, Besins, Theramex, Gedeon Richter; travel support from Gedeon Richter; S.S.R. is part of the Data Safety Monitoring Board of TTRANSPORT and deputy of the ESHRE Special Interest Group on Safety and Quality in ART; stock or stock options from IVI Lisboa, Clínica de Reprodução assistida Lda; equipment/medical writing/gifts from Roche Diagnostics and Ferring Pharmaceuticals. S.K.S. reports speakers' fees from Merck, Ferring, MSD, Pharmasure. HRV reports consulting and travel fees from Ferring Pharmaceuticals. The other authors have nothing to disclose. DISCLAIMER This guideline represents the views of ESHRE, which were achieved after careful consideration of the scientific evidence available at the time of preparation. In the absence of scientific evidence on certain aspects, a consensus between the relevant ESHRE stakeholders has been obtained. Adherence to these clinical practice guidelines does not guarantee a successful or specific outcome, nor does it establish a standard of care. Clinical practice guidelines do not replace the need for application of clinical judgment to each individual presentation, nor variations based on locality and facility type. ESHRE makes no warranty, express or implied, regarding the clinical practice guidelines and specifically excludes any warranties of merchantability and fitness for a particular use or purpose. (Full disclaimer available at www.eshre.eu/guidelines.) [ABSTRACT FROM AUTHOR]

Study Question: Which genes are confidently linked to human monogenic male infertility?Summary Answer: Our systematic literature search and clinical validity assessment reveals that a total of 78 genes are currently confidently linked to 92 human male infertility phenotypes.What Is Known Already: The discovery of novel male infertility genes is rapidly accelerating with the availability of next-generating sequencing methods, but the quality of evidence for gene-disease relationships varies greatly. In order to improve genetic research, diagnostics and counseling, there is a need for an evidence-based overview of the currently known genes.Study Design, Size, Duration: We performed a systematic literature search and evidence assessment for all publications in Pubmed until December 2018 covering genetic causes of male infertility and/or defective male genitourinary development.Participants/materials, Setting, Methods: Two independent reviewers conducted the literature search and included papers on the monogenic causes of human male infertility and excluded papers on genetic association or risk factors, karyotype anomalies and/or copy number variations affecting multiple genes. Next, the quality and the extent of all evidence supporting selected genes was weighed by a standardized scoring method and used to determine the clinical validity of each gene-disease relationship as expressed by the following six categories: no evidence, limited, moderate, strong, definitive or unable to classify.Main Results and the Role Of Chance: From a total of 23 526 records, we included 1337 publications about monogenic causes of male infertility leading to a list of 521 gene-disease relationships. The clinical validity of these gene-disease relationships varied widely and ranged from definitive (n = 38) to strong (n = 22), moderate (n = 32), limited (n = 93) or no evidence (n = 160). A total of 176 gene-disease relationships could not be classified because our scoring method was not suitable.Large Scale Data: Not applicable.Limitations, Reasons For Caution: Our literature search was limited to Pubmed.Wider Implications Of the Findings: The comprehensive overview will aid researchers and clinicians in the field to establish gene lists for diagnostic screening using validated gene-disease criteria and help to identify gaps in our knowledge of male infertility. For future studies, the authors discuss the relevant and important international guidelines regarding research related to gene discovery and provide specific recommendations for the field of male infertility.Study Funding/competing Interest(s): This work was supported by a VICI grant from The Netherlands Organization for Scientific Research (918-15-667 to J.A.V.), the Royal Society, and Wolfson Foundation (WM160091 to J.A.V.) as well as an investigator award in science from the Wellcome Trust (209451 to J.A.V.).Prospero Registration Number: None. [ABSTRACT FROM AUTHOR]

It is widely acknowledged that the responsible introduction of new assisted reproductive technologies (ARTs) requires preclinical safety research, including the use of animal models and human embryos. However, the moral sensitivity of human embryo research has led to regulations and guidance stating that human embryos may only be used for research that cannot also be conducted with animals. We call this the 'use animals first' (UAF) rule. In the field of ART research, this translates into the notion of an ideal chain of consecutive preclinical research steps, where research using human embryos may only be considered as a further step after promising results have been obtained in animals first. This may lead to research ethics committees requiring animal studies that are in fact a waste of time and money, while exposing animals to an infringement of their wellbeing for no good purpose. In this paper, we explore the possible moral arguments behind the UAF-rule and test their validity. We conclude that there are no convincing grounds for upholding this rule and recommend replacing it. [ABSTRACT FROM AUTHOR]

Sir, We read with great interest the article by [1] in I Human Reproduction i regarding the compliance of the published studies on WHO5 recommendations for basic semen analysis. This article is of great clinical significance for solving the problem of basic semen analysis standardization, and beneficial to promote strict adherence to semen analysis methods to reduce technical errors. [Extracted from the article]

STUDY QUESTION: Does the interdiction of sexual intercourse during Nativity and Lent fasting periods have any effect on when babies are conceived in Romania, in the 20th century? SUMMARY ANSWER: Based on date of birth records from the 20th century, Lent had a greater effect than the Nativity fast on conception within the Eastern Orthodox (ORTHD) population. WHAT IS KNOWN ALREADY: Seasonality of births (and therefore of conception) is affected by geographical factors (latitude, weather, day-length). Other demographic, economic and socio-cultural characteristics (education, ethnicity, religion) have been proved to have an influence on conception. STUDY DESIGN, SIZE, DURATION: The analyzed data consists of registered daily birth records for a long time series (35 429 points = 365 (days/year) x 97 years + 24 leap years), with 24 947 061 births in Romania over the period 1905-2001.The data were obtained from the 1992 and 2002 censuses. PARTICIPANTS/MATERIALS, SETTING, METHODS: Based on the reported birth date of each person, the estimated date of conception is computed using a standard gestation period of 280 days. The population was grouped into two categories (ORTHD and Non-Orthodox (NORTHD)) based on religious affiliation. Data analysis is performed in the same manner for both groups. Preliminary data analyses regarding seasonal variations in conception are considered first. Econometric models are applied and tested. The dependent variable in these models is the calculated date of conception, while the independent variables are: (i) religious affiliation; (ii) dates of Nativity and Lent fasts (the latter varies slightly from year to year); (iii) rural versus urban residence; (iv) length of day-light; (v) non-working days and (vi) trend. The models are tested for validity using analysis of variance while the regression coefficients are tested by the Student t-test. MAIN RESULTS AND THEROLEOFCHANCE: All models are statistically valid (P < 0.01); all regression coefficients for the ORTHD group are valid (P < 0.01, except for rurality between 1990 and 2001, with P < 0.05). The data analysis indicates smaller standard error bars on the parameters for the ORTHD group as compared with the NORTHD group. The conclusion is that religious affiliation is an important factor in date of conception. LIMITATIONS, REASONS FOR CAUTION: The data do not refer to all births during the analyzed period, but only to those persons still alive at the 1992 and 2002 censuses. The date of conception was estimated assuming 280 days for gestation, which is a medically accepted time interval but will undoubtedly vary. However, the primary independent variables (Lent and Nativity fast at 48 and 40 days, respectively) are long enough to overlap the uncertainty in the conception date following the sexual intercourse event. We also must assume that the religious affiliation of the parents is well defined, based on the information given by their offspring at census time, and is the same for both parents. WIDER IMPLICATIONS OF THE FINDINGS: Our findings are consistent with other studies, which show differences between religious groups on date of conception, although we reach different conclusions regarding the influence of weather on fertility in Romania. STUDY FUNDING/COMPETING INTEREST(S): B.V.I., M.A. and G.R. have no competing interests to declare. There is no connection to the current paper, but C.H. declares that (i) he is currently conducting a research titled 'Chronic Diseases' Direct Costs within the Romanian Health System' funded by Local American Working Group; (ii) his wife is employed to a Romanian company (A&D Pharma) that does business in the pharmaceutical sector. This paper is a part of G.R. and M.A. scientific activities in COST Action TDI2IO.Thiswork by C.H. was co-financed by the European Social Fund through project number POSDRU/I.5/S/59I84. [ABSTRACT FROM AUTHOR]

Study Question: How many twins are born in human populations and how has this changed over recent decades?Summary Answer: Since the 1980s, the global twinning rate has increased by a third, from 9.1 to 12.0 twin deliveries per 1000 deliveries, to about 1.6 million twin pairs each year.What Is Known Already: It was already known that in the 1980s natural twinning rates were low in (East) Asia and South America, at an intermediate level in Europe and North America, and high in many African countries. It was also known that in recent decades, twinning rates have been increasing in the wealthier parts of our world as a result of the rise in medically assisted reproduction (MAR) and delayed childbearing.Study Design, Size, Duration: We have brought together all information on national twinning rates available from statistical offices, demographic research institutes, individual survey data and the medical literature for the 1980-1985 and the 2010-2015 periods.Participants/materials, Setting, Methods: For 165 countries, covering over 99% of the global population, we were able to collect or estimate twinning rates for the 2010-2015 period. For 112 countries, we were also able to obtain twinning rates for 1980-1985.Main Results and the Role Of Chance: Substantial increases in twinning rates were observed in many countries in Europe, North America and Asia. For 74 out of 112 countries the increase was more than 10%. Africa is still the continent with highest twinning rates, but Europe, North America and Oceania are catching up rapidly. Asia and Africa are currently home to 80% of all twin deliveries in the world.Limitations, Reasons For Caution: For some countries, data were derived from reports and papers based on hospital registrations which are less representative for the country as a whole than data based on public administrations and national surveys.Wider Implications Of the Findings: The absolute and relative number of twins for the world as a whole is peaking at an unprecedented level. An important reason for this is the tremendous increase in medically assisted reproduction in recent decades. This is highly relevant, as twin deliveries are associated with higher infant and child mortality rates and increased complications for mother and child during pregnancy and during and after delivery.Study Funding/competing Interest(s): The contribution of CM was partially supported by the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (grant No 681546, FAMSIZEMATTERS), Nuffield College, and the Leverhulme Trust. The contribution of GP was partially supported by the French Agence Nationale de la Recherche (grant No ANR-18-CE36-0007-07). The authors declare no conflict of interest.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

Study Question: Is bacterial vaginosis (BV) associated with fecundability?Summary Answer: Women with BV may be at increased risk for sub-fecundity.What Is Known Already: While BV has been associated with poor IVF outcomes, the association between vaginal microbiota disruption and non-medically assisted conception has not been thoroughly explored.Study Design, Size, Duration: Kenyan women with fertility intent were enrolled in prospective cohort that included monthly preconception visits with vaginal fluid specimen collection and pregnancy testing. Four hundred fifty-eight women attempting pregnancy for ≤3 menstrual cycles at enrollment were eligible for this fecundability analysis.Participants/materials, Setting, Methods: At monthly preconception visits, participants reported the first day of last menstrual period and sexual behavior, underwent pregnancy testing and provided vaginal specimens. Discrete time proportional probabilities models were used to estimate fecundability ratios (FRs) and 95% CI in menstrual cycles with and without BV (Nugent score ≥ 7) at the visit prior to each pregnancy test. We also assessed the association between persistent BV (BV at two consecutive visits) and fecundability.Main Results and the Role Of Chance: Participants contributed 1376 menstrual cycles; 18.5% (n = 255) resulted in pregnancy. After adjusting for age, frequency of condomless sex and study site, BV at the visit prior to pregnancy testing was associated with a 17% lower fecundability (adjusted FR (aFR) 0.83, 95% CI 0.6-1.1). Persistent BV was associated with a 43% reduction in fecundability compared to cycles characterized by optimal vaginal health (aFR 0.57, 95% CI 0.4-0.8).Limitations, Reasons For Caution: Detection of vaginal microbiota disruption using Gram stain and a point-of-care test for elevated sialidase identified a non-optimal vaginal environment, but these non-specific methods may miss important relationships that could be identified by characterizing individual vaginal bacteria and bacterial communities using molecular methods. In addition, results may be subject to residual confounding by condomless sex as this was reported for the prior month rather than for the fertile window during each cycle.Wider Implications Of the Findings: Given the high global prevalence of BV and infertility, an association between BV and reduced fecundability could have important implications for a large number of women who wish to conceive. Multi-omics approaches to studying the vaginal microbiota may provide key insights into this association and identify potential targets for intervention.Study Funding/competing Interest(s): This work was supported by a National Institutes of Health grant (NICHD R01 HD087346-R.S.M.). R.S.M. received additional support for mentoring (NICHD K24 HD88229). E.M.L. was supported by pre- and post-doctoral fellowships (NIAID T32 AI07140, NICHD F32 HD100202). Data collection and management were made possible using REDCap electronic data capture tools hosted at the University of Washington's Institute of Translational Health Science supported by grants from NCATS/NIH (UL1 TR002319). The content of this paper is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. R.S.M. receives research funding, paid to the University of Washington, from Hologic Corporation, and has received honoraria for consulting from Lupin Pharmaceuticals. L.E.M. receives research funding, paid to the University of Washington, from Hologic Corporation, and has received honoraria for service on scientific advisory boards from Hologic and Nabriva Therapeutics.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

Study Question: Is testicular function associated within father-son pairs?Summary Answer: Familial resemblance in testis volume and serum markers of spermatogenesis was observed in father-son pairs.What Is Known Already: Studies suggest familial clustering of male subfertility and impaired spermatogenesis, but in men from the general population little is known about concordance in testicular function between fathers and sons.Study Design, Size, Duration: This cross-sectional study with simultaneous collection of data in fathers and sons included 72 pairs (144 fathers and sons), unselected regarding testicular function were included.Participants/materials, Setting, Methods: A subgroup of men from the background population and participating in a study on testicular function were asked permission to invite their fathers to participate in a similar setup. Fathers (median age of 53 years) and sons (median age of 19 years) participated in the same study setup including assessment of testis size, having a blood sample taken and analysed for serum levels of reproductive hormones (FSH, inhibin B, LH, testosterone, oestradiol, sex hormone-binding globulin (SHBG) and calculated free testosterone) and delivering a semen sample for assessment of traditional semen parameters. Mixed-effects models were fitted to estimate the familial resemblance as the proportion of variance in markers of testicular function due to shared factors for fathers and sons accounted for using random-effects. Variance components were calculated from both unadjusted and adjusted models.Main Results and the Role Of Chance: After adjustments, variance component analyses showed that familial resemblance between fathers and sons accounted for 48% (P < 0.001) of the variation in testicular volume, 32% (P = 0.009) of the variation in FSH, 31% (P = 0.009) of the variation in the inhibin B/FSH ratio, 33% (P = 0.007) and 45% (P < 0.001) of the variation in testosterone and free testosterone, respectively, and 31% (P = 0.009) of the variation in SHBG. None of the semen parameters were associated within father-son pairs.Limitations, Reasons For Caution: The present study may have lacked power to detect associations for semen quality, as large intra- and inter-individual variation occur in semen parameters.Wider Implications Of the Findings: In this study, testis volume, serum testosterone and serum markers of spermatogenesis including FSH were associated in fathers and sons, suggesting an impact of paternal genetics for testicular function in the son. However, the estimated familial resemblance for spermatogenesis markers highlights that other factors, such as maternal genetics and prenatal as well as adult exposures, are also of major importance for testicular function.Study Funding/competing Interest(s): The study has received funding from Danish Health Authority, Research Fund of the Capital Region of Denmark and Independent Research Fund Denmark (8020-00218B). None of the funders had any role in the study design, collection, analysis or interpretation of data, writing of the paper of publication decisions. The authors have nothing to disclose.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

Study Question: Is it possible to evaluate the methylome of individual oocytes to investigate the DNA methylome alterations in metaphase II (MII) oocytes with reduced embryo developmental potential?Summary Answer: The DNA methylome of each human first polar body (PB1) closely mirrored that of its sibling MII oocyte; hypermethylated long interspersed nuclear element (LINE) and long terminal repeats (LTRs) and methylation aberrations in PB1 promoter regions may indicate poor embryo development.What Is Known Already: The developmental potential of an embryo is determined by the oocyte's developmental competence, and the PB1 is a good substitute to examine the chromosomal status of the corresponding oocyte. However, DNA methylation, a key epigenetic modification, also regulates gene expression and embryo development.Study Design, Size, Duration: Twelve pairs of PB1s and sibling MII oocytes were biopsied and sequenced to compare their methylomes. To further investigate the methylome of PB1s and the potential epigenetic factors that may affect oocyte quality, MII oocytes (n = 74) were fertilized through ICSI, while PB1s were biopsied and profiled to measure DNA methylation. The corresponding embryos were further cultured to track their development potential. The oocytes and sperm samples used in this study were donated by healthy volunteers with signed informed consent.Participants/materials, Setting, Methods: Single-cell methylome sequencing was applied to obtain the DNA methylation profiles of PB1s and oocytes. The DNA methylome of PB1s was compared between the respective group of oocytes that progressed to blastocysts and the group of oocytes that failed to develop. DNA methylation levels of corresponding regions and differentially methylated regions were calculated using customized Perl and R scripts. RNA-seq data were downloaded from a previously published paper and reanalysed.Main Results and the Role Of Chance: The results from PB1-MII oocyte pair validated that PB1 contains nearly the same methylome (average Pearson correlation is 0.92) with sibling MII oocyte. LINE and LTR expression increased markedly after fertilization. Moreover, the DNA methylation levels in LINE (including LINE1 and LINE2) and LTR were significantly higher in the PB1s of embryos that could not reach the blastocyst stage (Wilcoxon-Matt-Whitney test, P < 0.05). DNA methylation in PB1 promoters correlated negatively with gene expression of MII oocyte. Regarding the methylation status of the promoter regions, 66 genes were hypermethylated in the developmental arrested group, with their related functions (significantly enriched in several Gene Ontology terms) including transcription, positive regulation of adenylate cyclase activity, mitogen-activated protein kinase (MAPK) cascade and intracellular oestrogen receptor signalling pathway.Large Scale Data: N/A.Limitations, Reasons For Caution: Data analysis performed in this study focused on the competence of human oocytes and compared them with maternal genetic and epigenetic profiles. Therefore, data regarding the potential regulatory roles of paternal genomes in embryo development are lacking.Wider Implications Of the Findings: The results from PB1-oocyte pairs demonstrated that PB1s shared similar methylomes with their sibling oocytes. The selection of the good embryos for transfer should not only rely on morphology but also consider the DNA methylation of the corresponding PB1 and therefore MII oocyte. The application of early-stage analysis of PB1 offers an option for high-quality oocyte and embryo selection, which provides an additional tool for elective single embryo transfer in assisted reproduction.Study Funding/competing Interest(s): This study was supported by the National Key Research and Development Program of China (2018YFC1004003, 2017YFA0103801), the National Natural Science Foundation of China (81730038, 3187144, 81521002) and the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA16020703). The authors have no conflicts of interest to declare. [ABSTRACT FROM AUTHOR]

STUDY QUESTION Does maternal infection with severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2) in first trimester pregnancy have an impact on the fetal development as measured by nuchal translucency thickness and pregnancy loss? SUMMARY ANSWER Nuchal translucency thickness at the first trimester scan was not significantly different in pregnant women with versus without SARS-CoV-2 infection in early pregnancy and there was no significantly increased risk of pregnancy loss in women with SARS-CoV-2 infection in the first trimester. WHAT IS KNOWN ALREADY Pregnant women are more vulnerable to viral infections. Previous coronavirus epidemics have been associated with increased maternal morbidity, mortality and adverse obstetric outcomes. Currently, no evidence exists regarding possible effects of SARS-CoV-2 in first trimester pregnancies. STUDY DESIGN, SIZE, DURATION Cohort study of 1019 women with a double test taken between 17 February and 23 April 2020, as a part of the combined first trimester risk assessment, and 36 women with a first trimester pregnancy loss between 14 April and 21 May 2020, prior to the double test. The study period was during the first SARS-CoV-2 epidemic wave in Denmark. PARTICIPANTS/MATERIALS, SETTING, METHODS Cohort 1 included pregnant women with a double test taken within the study period. The excess serum from each double test was analyzed for SARS-CoV-2 antibodies. Results were correlated to the nuchal translucency thickness and the number of pregnancy losses before or at the time of the first trimester scan. Cohort 2 included women with a pregnancy loss before the gestational age for double test sample. Serum from a blood test taken the day the pregnancy loss was identified was analyzed for SARS-CoV-2 antibodies. The study was conducted at a public university hospital serving ∼12% of pregnant women and births in Denmark. All participants in the study provided written informed consent. MAIN RESULTS AND THE ROLE OF CHANCE Eighteen (1.8%) women had SARS-CoV-2 antibodies in the serum from the double test suggestive of SARS-CoV-2 infection in early pregnancy. There was no significant difference in nuchal translucency thickness for women testing positive for previous SARS-CoV-2 infection (n = 16) versus negative (n = 966) (P  = 0.62). There was no significantly increased risk of pregnancy loss for women with antibodies (n = 1) (OR 3.4, 0.08–24.3 95% CI, P  = 0.27). None of the women had been hospitalized due to SARS-CoV-2 infection. None of the women with pregnancy loss prior to the double test (Cohort 2) had SARS-CoV-2 antibodies. LIMITATIONS, REASONS FOR CAUTION These results may only apply to similar populations and to patients who do not require hospitalization due to SARS-CoV-2 infection. A limitation of the study is that only 1.8% of the study population had SARS-CoV-2 antibodies suggestive of previous infection. WIDER IMPLICATION OF THE FINDINGS Maternal SARS-CoV-2 infection had no effect on the nuchal translucency thickness and there was no significantly increased risk of pregnancy loss for women with SARS-CoV-2 infection in first trimester pregnancy. Evidence concerning COVID-19 in pregnancy is still limited. These data indicate that infection with SARS-CoV-2 in not hospitalized women does not pose a significant threat in first trimester pregnancies. Follow-up studies are needed to establish any risk to a fetus exposed to maternal SARS-CoV-2 infection. STUDY FUNDING/COMPETING INTEREST(S) Prof. H.S.N. and colleagues received a grant from the Danish Ministry of Research and Education for research of COVID-19 among pregnant women. The Danish government was not involved in the study design, data collection, analysis, interpretation of data, writing of the report or decision to submit the paper for publication. A.I. J.O.-L. J.B.-R. D.M.S. J.E.-F. and E.R.H. received funding from a Novo Nordisk Foundation (NNF) Young Investigator Grant (NNF15OC0016662) and a Danish National Science Foundation Center Grant (6110-00344B). A.I. received a Novo Scholarship. J.O.-L. is funded by an NNF Pregraduate Fellowship (NNF19OC0058982). D.W. is funded by the NNF (NNF18SA0034956, NNF14CC0001, NNF17OC0027594). A.M.K. is funded by a grant from the Rigshospitalet's research fund. H.S.N. has received speaker's fees from Ferring Pharmaceuticals, Merck Denmark A/S and Ibsa Nordic (outside the submitted work). N.l.C.F. has received a grant from Gedeon Richter (outside the submitted work). A.M.K. has received speaker's fee from Merck (outside the submitted work). The other authors did not report any potential conflicts of interest. TRIAL REGISTRATION NUMBER N/A [ABSTRACT FROM AUTHOR]

Study Question: Is there a difference in the odds of a live birth following blastocyst- versus cleavage-stage embryo transfer in the first complete cycle of IVF?Summary Answer: After adjusting for indication bias, there was not enough evidence to suggest a difference in the odds of live birth following blastocyst- versus cleavage-stage embryo transfer in the first complete cycle of IVF.What Is Known Already: Replacement of blastocyst-stage embryos has become the dominant practice in IVF but there is uncertainty about whether this technique offers an improved chance of cumulative live birth over all fresh and frozen-thawed embryo transfer attempts associated with a single oocyte retrieval.Study Design, Size, Duration: National population-based retrospective cohort study of 100 610 couples who began their first IVF/ICSI treatment at a licenced UK clinic between 1 January 1999 and 30 July 2010.Participants/materials, Setting, Methods: Data from the Human Fertilisation and Embryology Authority (HFEA) register on IVF/ICSI treatments using autologous gametes between 1999 and 2010 were analysed. The primary outcome was the live birth rate over the first complete cycle of IVF. Cumulative live birth rates (CLBR) were compared for couples who underwent blastocyst and cleavage transfer, and the adjusted odds of live birth over the first complete cycle were estimated for each group using binary logistic regression. This analysis was repeated within groups of female age, oocytes collected and primary versus secondary infertility. Inverse probability of treatment weighting was used to account for the imbalance in couple characteristics between treatment groups.Main Results and the Role Of Chance: In total, 94 294 (93.7%) couples had a cleavage-stage embryo transfer while 6316 (6.3%) received blastocysts. Over the first complete cycle of IVF/ICSI (incorporating all fresh and frozen-thawed embryo transfers associated with the first oocyte retrieval), the CLBR was increased in those who underwent blastocyst transfer (56.5%) compared to cleavage-stage embryo transfer (34.8%). However, after accounting for the imbalance between exposures, blastocyst transfer did not significantly influence the odds of live birth over the first complete cycle (adjusted odds ratio: 1.03 (0.96, 1.10)).Limitations, Reasons For Caution: Limitations of our study include the retrospective nature of the HFEA dataset and availability of linked data up until 2010. We were unable to adjust for some confounders, such as smoking status, BMI and embryo quality, as these data are not collected at national level by the HFEA. Similarly, there may be unknown couple, treatment or clinic variables that may influence our results. We were unable to assess the intended stage of embryo transfer for women who did not have an embryo replaced, and therefore excluded them from our study. Perinatal outcomes were not included in our analyses and would be a useful basis for future study.Wider Implications Of the Findings: Our findings show that blastocyst-stage embryo transfer may offer an improved chance of live birth in both the first fresh and the first complete cycle of IVF/ICSI compared to cleavage-stage transfer, even in couples with typically poorer prognoses. Where possible, offering blastocyst transfer to a wider range of couples may increase cumulative success rates.Study Funding/competing Interest(s): N.J.C. received a Wolfson Foundation Intercalated Degree Research Fellowship funded by the Wolfson Foundation, through the Royal College of Physicians. This work was supported by a Chief Scientist Office Postdoctoral Training Fellowship in Health Services Research and Health of the Public Research (Ref PDF/12/06) held by D.J.M. The views expressed here are those of the authors and not necessarily those of the Chief Scientist Office or the Wolfson Foundation. The funders did not have any role in the study design; in the collection, analysis and interpretation of data; in the writing of the report; nor in the decision to submit the paper for publication. None of the authors has any conflicts of interest to declare.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

Over the years, the demand for ART with donated embryos has increased. Treatment can be performed using donated 'surplus embryos' from IVF treatment or with embryos intentionally created through so-called 'double gamete donation'. Embryo donation is particularly sensitive because treatment results in the absence of a genetic link between the parent(s) and the child, creating complex family structures, including full genetic siblings living in another family in the case of surplus embryo donation. In this paper, we explore the ethical acceptability of embryo donation in light of the similarities and differences between surplus embryo donation and double gamete donation. We will argue that no overriding objections to either form of embryo donation exist. First of all, ART with donated embryos respects patients' reproductive autonomy by allowing them to experience gestational parenthood. It also respects IVF patients' reproductive autonomy by providing an additional option to discarding or donating surplus embryos to research. Second, an extensive body of empirical research has shown that a genetic link between parent and child is not a condition for a loving caring relationship between parent(s) and child. Third, the low moral status of a pre-implantation embryo signifies no moral duty for clinics to first use available surplus embryos or to prevent the development of (more) surplus embryos through double gamete donation. Fourth, there is no reason to assume that knowledge of having (full or half) genetically related persons living elsewhere provides an unacceptable impact on the welfare of donor-conceived offspring, existing children of the donors, and their respective families. Thus, patients and clinicians should discuss which form of ART would be suitable in their specific situation. To guarantee ethically sound ART with donated embryos certain conditions have to be met. Counselling of IVF patients should involve a discussion on the destination of potential surplus embryos. When counselling donors and recipient(s) a discussion of the significance of early disclosure of the child's mode of conception, the implications of having children raised in families with whom they share no genetic ties, expectations around information-exchange and contact between donor and recipient families or genetically related siblings is warranted. Importantly, conclusions are mainly drawn from results of empirical studies on single gamete donation families. To evaluate the welfare of families created through surplus embryo donation or double gamete donation additional empirical research on these particular families is warranted. [ABSTRACT FROM AUTHOR]

In IVF/ICSI treatment, the FSH starting dose is often increased in predicted low responders from the belief that it improves the chance of having a baby by maximizing the number of retrieved oocytes. This intervention has been evaluated in several randomized controlled trials, and despite a slight increase in the number of oocytes-on average one to two more oocytes in the high versus standard dose group-no beneficial impact on the probability of a live birth has been demonstrated (risk difference, -0.02; 95% CI, -0.11 to 0.06). Still, many clinicians and researchers maintain a highly ingrained belief in 'the more oocytes, the better'. This is mainly based on cross-sectional studies, where the positive correlation between the number of retrieved oocytes and the probability of a live birth is interpreted as a direct causal relation. If the latter would be present, indeed, maximizing the oocyte number would benefit our patients. The current paper argues that the use of high FSH doses may not actually improve the probability of a live birth for predicted low responders undergoing IVF/ICSI treatment and exemplifies the flaws of directly using cross-sectional data to guide FSH dosing in clinical practice. Also, difficulties in the de-implementation of the increased FSH dosing strategy are discussed, which include the prioritization of intermediate outcomes (such as cycle cancellations) and the potential biases in the interpretation of study findings (such as confirmation or rescue bias). [ABSTRACT FROM AUTHOR]

Study Question: Is there a difference in testicular function in early adulthood between men born with cryptorchidism and men born with normally descended testes?Summary Answer: In men from the general population, a history of cryptorchidism was associated with lower total testis volume and impaired semen quality as well as altered serum levels of reproductive hormones.What Is Known Already: The association between cryptorchidism and testicular function is well documented in studies based on sub-fertile or infertile men recruited from a clinical setting. However, the association has not previously been investigated in men from the general population, who were unselected regarding fertility status.Study Design, Size, Duration: This is a cross-sectional population-based study of 6376 young Danish men examined from 1996 to 2017.Participants/materials, Setting, Methods: This study is based on young men from the greater Copenhagen area, Denmark (median age of 19 years) who were unselected regarding fertility status and semen quality. The young men delivered a semen sample, had a blood sample drawn and underwent a physical examination including assessment of testis volume. Participants completed a questionnaire regarding cryptorchidism at birth, current lifestyle and their mother's pregnancy, after consulting their mother. The differences in markers of testicular function, including testis volume, semen parameters and reproductive hormones between men with and without a history of cryptorchidism were investigated with multiple linear regression analyses.Main Results and the Role Of Chance: The participation rate was 24% for the entire study period. Overall, a history of cryptorchidism was associated with reduced testicular function. In the adjusted models, a history of cryptorchidism was associated with a 3.5 ml lower total testis volume, determined by orchidometer (P < 0.001), 28% lower sperm concentration (95% CI: -37 to -20) and 26% lower inhibin B/FSH ratio (95% CI: -50 to -22) compared to men without a history of cryptorchidism, suggesting a reduced spermatogenetic capacity. Men with a history of cryptorchidism also had a slightly reduced Leydig cell function expressed as a 6% lower testosterone/LH ratio (95% CI: -12 to -0.7). The significant effect sizes and different markers of testicular function pointing in the same direction across the different models based on a large sample size support that the results are not chance findings.Limitations, Reasons For Caution: Information on cryptorchidism at birth and treatment modus was obtained by retrospective self-report, and each participant only delivered one semen sample.Wider Implications Of the Findings: The results suggest that men with a history of cryptorchidism could be at increased risk of experiencing fertility problems. However, among these men there is a wide variation in semen quality and further research is needed in order to identify the subgroup of boys born with cryptorchidism who are at the greatest risk of impaired semen quality when reaching adulthood.Study Funding/competing Interest(s): The study received financial support from the Research fund of Rigshospitalet, Copenhagen University Hospital; the European Union (Contract numbers BMH4-CT96-0314, QLK4-CT-1999-01422, QLK4-CT-2002-00603. FP7/2007-2013, DEER Grant agreement no. 212844); the Danish Ministry of Health; the Danish Environmental Protection Agency; A.P. Møller and wife Chastine McKinney Møllers Foundation; and Svend Andersens Foundation. None of the founders had any role in the study design, collection, analysis or interpretation of data, writing of the paper or publication decisions. The authors have nothing to declare.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

Study Question: Can we develop a web-based sex education programme (programme running in a web browser) that addresses the needs of subfertile couples who are advised expectant management for at least 6 months?Summary Answer: The 'Pleasure & Pregnancy' programme addresses couples' needs, is likely to improve couples' sexual functioning, and is subsequently hypothesised to improve the chance of natural pregnancy.What Is Known Already: According to professional guidelines (e.g. the Netherlands and UK) couples with unexplained subfertility and a good chance of natural pregnancy, should be advised at least 6 months of expectant management. Adherence to expectant management is challenging as couples and gynaecologist prefer a more active approach. Targeting sexuality may be useful as subfertility is a risk factor for decreased sexual functioning.Study Design, Size, Duration: A novel programme was developed according to the three steps of the Medical Research Councils' (MRC) framework. First, relevant literature was explored. Second, an interdisciplinary expert panel developed a theory (based on a systematic literature review and patient interviews) on how the chance of natural conception can be improved. Third, the expected process and outcomes were modelled.Participants/materials, Setting, Methods: Two licenced clinical sexologists, two gynaecologists, a clinical embryologist and two midwife-researchers, all from Belgium and the Netherlands, proposed components for the sex education programme. PubMed was searched systematically for randomised controlled trials (RCTs) evaluating the proposed components in different patient populations. The needs of 12 heterosexual Dutch or Belgian couples who were advised expectant management were explored with in-depth interviews. The content and delivery characteristics of the novel programme were described in detail with the aid of 'Intervention Taxonomy'. To model the outcomes, a protocol for an RCT was designed, registered and submitted for publication.Main Results and the Role Of Chance: To help maintain or improve sexual functioning, mainly pleasure, and hence increase pregnancy rates, the web-based Pleasure & Pregnancy programme contains a combination of psychosexual education and couple communication, mindfulness and sensate focus exercises. Information on the biology of conception and interaction with fertility clinic staff and peers were added based on couples' needs to increase potential acceptability.Limitations and Reason For Caution: This paper outlines the development phase of a sex education programme according to the MRC-framework. Whether the Pleasure & Pregnancy programme actually is acceptable, improves sexual functioning, increases pregnancy rates and is cost-effective remains to be determined.Wider Implications Of the Findings: No previous interactive web-based sex education programme has aimed to increase the natural pregnancy rate of subfertile couples by targeting their sexual pleasure. The Pleasure & Pregnancy programme addresses couples' needs and its effect on sexual functioning and pregnancy rate is plausible but remains to be demonstrated by an RCT which is currently ongoing.Study Funding/competing Interest(s): Funding was provided by The Netherlands Organisation for Health Research and Development (ZonMw), Flanders Research Foundation and the University of Amsterdam. C.B.L. is editor-in-chief of Human Reproductionbut was blinded to all parts of the peer review process. The remaining authors have no conflict of interest to report.Trial Registration Number: Not applicable. [ABSTRACT FROM AUTHOR]

The matter of disclosure of donor conception to donor offspring is a very contentious issue. A frequently mentioned argument is that disclosure is in the best interest of the child. The objectives of this paper are 2-fold: first, to find out whether there are any measureable, stable differences in the psychological well-being of donor offspring who are informed of the mode of their conception compared to those who are not, and second, to find out what is being done with the evidence. We found that there exists no empirical evidence of differences in psychological well-being of donor offspring in disclosing or nondisclosing families. Regarding the age of disclosure, the findings are inconclusive. Some studies indicate no difference and some show slight positive effects of early disclosure. We also found that authors tend to ignore their own findings when formulating recommendations and that the recommendations are based on implicit moral premises. We conclude that disclosure, and directive counseling towards disclosure, cannot be justified by the welfare of the donor offspring. [ABSTRACT FROM AUTHOR]

This opinion paper addresses the literature regarding repeated implantation failure (RIF) in IVF embryo transfer programmes. We provide several lines of discussion as to why such diagnosis might be wrong, why it should not be a call for action or a reason to change the course of treatment, and how RIF biases the quality of the publications and leads to the use of unnecessary and costly adjuvant procedures beyond basic IVF. We argue that these costly add-on procedures are being offered to patients in this highly privatized sector to prevent them from quitting the programme and as a by-product to increase the clinic income. The patients, on the other hand, often equate lucrative hi-tech procedures with possible success and request them despite the lack of proof of the efficacy of most of the procedures. [ABSTRACT FROM AUTHOR]

Study Question: Is an MRI classification of deep pelvic endometriosis (DE) able to correctly predict the risk of DE surgery.Summary Answer: A new radiological classification, that we have called the deep pelvic endometriosis index (dPEI) classification, is accurate and reproducible to assess the extension of the disease in central and lateral compartments and well correlated with operating time, hospital stay duration and the risk of voiding dysfunction.What Is Known Already: Few imaging classifications are currently available to predict the extent of DE to help preoperative assessment of surgical outcomes and provide the patient with objective information about the risk of surgical complications.Study Design, Size, Duration: Retrospective monocentric observational study was conducted between 01 January 2017 and 31 December 2018 and included 150 women (mean age = 34.5 years, 20-52 years) with DE on MRI and who subsequently underwent surgery.Participants/materials, Setting, Methods: Two radiologists independently graded the disease according to MRI-based Enzian classification (A (rectovaginal septum and vagina locations), B (uterosacral locations) and C (rectosigmoid locations)) and a new radiological classification, that we have called the dPEI, that grades the severity of DE as: mild, moderate or severe DE. MRI findings and classification were correlated with surgical and pathological results.Main Results and the Role Of Chance: MRI-based and surgical Enzian classifications were concordant for A lesions in 78.7% (118/150), for B lesions in 34.7% (52/150) and for C lesions in 82.7% (124/150). Operating time and hospital stays were longer in Group A2 (rectovaginal septum and vagina, 1-3 cm) compared to A0, B2 (uterosacral, 1-3 cm) compared to B0, C3 (rectosigmoid >3 cm) compared to C2 (rectosigmoid 1-3 cm) or C0 (P < 0.001), in severe compared to moderate DE patients, and in moderate compared to mild extensive patients (P < 0.01). Patients with vaginal or rectosigmoid involvement were respectively six and three times more likely to experience high-grade complications according to Clavien-Dindo classification than patients without vaginal or rectosigmoid disease (P < 0.001). Postoperative voiding dysfunction was correlated with A lesions (odds ratio (OR) = 6.82, 95% CI 2.34-20.5), moderate or severe DE (OR = 4.15, 95% CI 1.26-17.9), the presence of at least unilateral lateral pelvic involvement (OR = 3.6, 95% CI 1.14-11.2, P = 0.03) and C lesions (OR = 2.6, 95% CI 1.03-6.8, P < 0.01).Limitations, Reasons For Caution: The study was conducted in an expert center and needs to be validated in a multicenter study. There is a limited number of patients with lateral pelvic endometriosis beyond the parietal fascia, probably due to the low prevalence of this disease presentation.Wider Implications Of the Findings: MRI imaging can be used to accurately predict postoperative complications for women with DE. This may help the clinician to preoperatively inform a patient about the risks of surgery. Larger clinical studies are required to validate these results.Study Funding/competing Interest(s): No external funding was used for this study. I.T.N.: Remunerated lecture GE, Hologic, Guerbet, Canon; Advisory board: Siemens - These relationships are on the topic of breast imaging, not related to the topic of this paper. Other coauthors have no conflict of interest to declare.Trial Registration Number: Not applicable. [ABSTRACT FROM AUTHOR]

An increasing number of researchers have alluded to the potential benefit of deferring the transfer of embryos produced during assisted reproductive technologies (ARTs) away from ovarian stimulation, using cryopreservation to enable this. The scientific evidence that may justify this recent trend in the use of the so-called 'freeze-all strategy' includes early, mostly small randomised controlled trials that have demonstrated an increase in live birth rates after elective embryo cryopreservation in certain patient populations, as well as evidence from cohort studies and retrospective analyses. What are the risks and benefits of freeze-all strategies in ART, who are the patients in whom it is likely to be advantageous, and does the current evidence allow us to identify situations when deciding that a fresh embryo transfer would be counter-productive? ART professionals are often faced with challenging clinical decisions regarding the best course of treatment for their patient. The purpose of this opinion paper is to provide a clinical guide for whether to perform a fresh embryo transfer or to opt for freezing all embryos in specific situations. [ABSTRACT FROM AUTHOR]

Study Question: Do randomised controlled trials (RCTs) evaluating endometrial scratching suffer from methodological issues including insufficient trial registration, statistical errors or irreproducibility, randomisation errors or miscellaneous issues?Summary Answer: The majority of RCTs investigating endometrial scratching have methodological issues.What Is Known Already: A large number of small RCTs investigating the effectiveness of endometrial scratching prior to in vitro fertilisation (IVF) and intrauterine insemination (IUI)/intercourse have reported favourable findings. Subsequently, systematic reviews incorporating these RCTs yielded meta-analyses in favour of endometrial scratching. Endometrial scratching has been widely adopted by infertility specialists around the world. Recently, an international RCT including 1364 women reported no benefit from endometrial scratching before IVF.Study Design, Size, Duration: We evaluated several methodological issues of RCTs investigating the effectiveness of endometrial scratching prior to IVF and IUI/intercourse. We identified 25 RCTs for IVF and 12 RCTs for IUI/intercourse with full-text publication.Participants/materials, Setting, Methods: We assessed the RCTs on the following criteria: adequacy of trial registration, statistical issues (description of statistical methods and reproducibility of univariable statistical analysis), excessive similarity or difference in baseline characteristics that is not compatible with chance (Monte Carlo simulations and Kolmogorov-Smirnov test) and miscellaneous methodological issues.Main Results and the Role Of Chance: Of 25 RCTs evaluating endometrial scratching prior to IVF, only eight (32%) had adequate trial registration. In total, 10 (40%) RCTs had issues regarding statistical methods. Nine (69%, 13 applicable) RCTs had at least one inconsistency between reported and reproduced univariable statistical analysis for categorical baseline/intermediate characteristics. Statistical results of at least one outcome were not reproducible in 14 (74%, 19 applicable) RCTs. Only two (8%) RCTs had none of the above issues. Suggested by the simulations, these RCTs did not significantly violate the null hypothesis that the baseline characteristics were the results of a properly conducted randomisation process (P = 0.4395).Of 12 IUI/intercourse RCTs, only 2 (17%) had adequate trial registration. In total, five (42%) studies had issues of statistical methods. Inconsistency between reported and reproduced univariable analysis for baseline/intermediate categorical variable(s) was found in four (57%, 7 applicable) RCTs. Statistical analysis was not reproducible for at least one outcome in eight (80%, 10 applicable) studies. All RCTs had at least one of the above issues. These RCTs were inconsistent with the null hypothesis that their baseline characteristics were the results of proper randomised allocation (P = 1.659*10-7).Limitations, Reasons For Caution: We were unable to assess RCTs which were not published as full-text papers. We could not analyse individual participant data to investigate possible reasons for statistical inconsistencies. The method to infer the likelihood of proper random sampling rests on assumptions including independent baseline characteristics, simple randomisation and no publication bias.Wider Implications Of the Findings: The methodological issues common to RCTs evaluating endometrial scratching may have biased the results of the trials. Further development and validation of these novel methods may be helpful for the critical appraisal of RCTs.Study Funding/competing Interest(s): No external funding was sought to support this work. B.W.M. is supported by a National Health Medical Research Council (NHMRC) Practitioner Fellowship (GNT1082548). B.W.M. reports consultancy for ObsEva, Merck and Guerbet. D.W. is supported by a grant from the Paracelsus Medical University Salzburg, Austria (PMU Research Fund-PMU FFF Number: L-18/02/006-WET) and by Drs Haackert Foundation, Germany. S.L. is an author of a trial included in this study, an author of an included systematic review and a Cochrane editor. All other authors have no conflicts of interest.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

Study Question: Does maternal smoking in early pregnancy affect metallothionein 1 and 2 (MT1 and MT2) mRNA and protein expression in first trimester placenta or embryonic/fetal liver?Summary Answer: In the first trimester, MT protein expression is seen only in liver, where smoking is associated with a significantly reduced expression.What Is Known Already: Zinc homeostasis is altered by smoking. Smoking induces MT in the blood of smokers properly as a result of the cadmium binding capacities of MT. In term placenta MT is present and smoking induces gene and protein expression (MT2 in particular), but the MT presence and response to smoking have never been examined in first trimester placenta or embryonic/fetal tissues.Study Design, Size, Duration: Cross sectional study where the presence of MT mRNA and protein was examined at the time of the abortion. The material was collected with informed consent after surgical intervention and frozen immediately. For protein expression analysis, liver tissue originating from smoking exposed n = 10 and unexposed n = 12 pregnancies was used. For mRNA expression analyses, placental tissue originating from smokers n = 19 and non-smokers n = 23 and fetal liver tissue from smoking exposed n = 16 and smoking unexposed pregnancies n = 13, respectively, were used.Participants/materials, Setting, Methods: Tissues were obtained from women who voluntarily and legally chose to terminate their pregnancy between gestational week 6 and 12. Western blot was used to determine the protein expression of MT, and real-time PCR was used to quantify the mRNA expression of MT2A and eight MT1 genes alongside the expression of key placental zinc transporters: zinc transporter protein-1 (ZNT1), Zrt-, Irt-related protein-8 and -14 (ZIP8 and ZIP14).Main Results and the Role Of Chance: A significant reduction in the protein expression of MT1/2 in liver tissue (P = 0.023) was found by western blot using antibodies detecting both MT forms. Overall, a similar tendency was observed on the mRNA level although not statistically significant. Protein expression was not present in placenta, but the mRNA regulation suggested a down regulation of MT as well. A suggested mechanism based on the known role of MT in zinc homeostasis could be that the findings reflect reduced levels of easily accessible zinc in the blood of pregnant smokers and hence a reduced MT response in smoking exposed fetal/embryonic tissues.Limitations and Reasons For Caution: Smoking was based on self-reports; however, our previous studies have shown high consistency regarding cotinine residues and smoking status. Passive smoking could interfere but was found mainly among smokers. The number of fetuses was limited, and other factors such as medication and alcohol might affect the findings. Information on alcohol was not consistently obtained, and we cannot exclude that it was more readily obtained from non-users. In the study, alcohol consumption was reported by a limited number (less than 1 out of 5) of women but with more smokers consuming alcohol. However, the alcohol consumption reported was typically limited to one or few times low doses. The interaction between alcohol and smoking is discussed in the paper. Notably we would have liked to measure zinc status to test our hypothesis, but maternal blood samples were not available.Wider Implications Of the Findings: Zinc deficiency-in particular severe zinc deficiency-can affect pregnancy outcome and growth. Our findings indicate that zinc homeostasis is also affected in early pregnancy of smokers, and we know from pilot studies that even among women who want to keep their babies, the zinc status is low. Our findings support that zinc supplements should be considered in particular to women who smoke.Study Funding/competing Interest(s): We thank the Department of Biomedicine for providing laboratory facilities and laboratory technicians and the Lundbeck Foundation and Læge Sofus Carl Emil Friis og Hustru Olga Doris Friis Legat for financial support. The authors have no competing interests to declare.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

Study Question: How did general practitioners (GPs) (family physicians) manage infertility in females and males in primary care between 2000 and 2016?Summary Answer: The number of GP infertility consultations for females increased 1.6 folds during the study period, with 42.9% of consultations resulting in a referral to a fertility clinic or specialist, compared to a 3-fold increase in the number of consultations for men, with 21.5% of consultations resulting in a referral.What Is Known Already: Infertility affects one in six couples and is expected to increase with the trend to later childbearing and reports of declining sperm counts. Despite GPs often being the first contact for infertile people, very limited information is available on the management of infertility in primary care.Study Design, Size, Duration: Data from the Bettering the Evaluation and Care of Health programme were used, which is a national study of Australian primary care (general practice) clinical activity based on 1000 ever-changing, randomly selected GPs involved in 100 000 GP-patient consultations per year between 2000 and 2016.Participants/materials, Setting, Methods: Females and males aged 18-49 years attending GPs for the management of infertility were included in the study. Details recorded by GPs included patient characteristics, problems managed and management actions (including counselling/education, imaging, pathology, medications and referrals to specialists and fertility clinics). Analyses included trends in the rates of infertility consultations by sex of patient, descriptive and univariate analyses of patient characteristics and management actions and multivariate logistic regression to determine which patient and GP characteristics were independently associated with increased rates of infertility management and referrals.Main Results and the Role Of Chance: The rate of infertility consultations per capita increased 1.6 folds for women (17.7-28.3 per 1000 women aged 18-49 years) and 3 folds for men over the time period (3.4-10.2 per 1000 men aged 18-49 years). Referral to a fertility clinic or relevant specialist occurred in 42.9% of female infertility consultations and 21.5% of male infertility consultations. After controlling for age and other patient characteristics, being aged in their 30s, not having income assistance, attending primary care in later years of the study and coming from a non-English-speaking background, were associated with an increased likelihood of infertility being managed in primary care. In female patients, holding a Commonwealth concession card (indicating low income), living in a remote area and having a female GP all indicated a lower adjusted odds of referral to a fertility clinic or specialist.Limitations, Reasons For Caution: Data are lacking for the period of infertility and infertility diagnosis, which would provide a more complete picture of the epidemiology of treatment-seeking behaviour for infertility. Australia's universal insurance scheme provides residents with access to a GP, and therefore these findings may not be generalizable to other settings.Wider Implications Of the Findings: This study informs public policy on how infertility is managed in primary care in different patient groups. Whether the management actions taken and rates of secondary referral to a fertility clinic or specialist are appropriate warrants further investigation. The development of clinical practice guidelines for the management of infertility would provide a standardized approach to advice, investigations, treatment and referral pathways in primary care.Study Funding/competing Interest(s): This paper is part of a study being funded by an Australian National Health and Medical Research Council project grant APP1104543. G.C. reports that she is an employee of The University of New South Wales (UNSW) and Director of the National Perinatal Epidemiology and Statistics Unit (NPESU), UNSW. The NPESU manages the Australian and New Zealand Assisted Reproductive Technology Database on behalf of the Fertility Society of Australia. W.L. reports being a part-time paid employee and minor shareholder of Virtus Health, a fertility company. R.N. reports being a small unitholder in a fertility company, receiving grants for research from Merck and Ferring and speaker travel grants from Merck.Trial Registration Number: NA. [ABSTRACT FROM AUTHOR]

Study Question: Is the presence or absence of certain vaginal bacteria associated with failure or success to become pregnant after an in vitro fertilization (IVF) or IVF with intracytoplasmic sperm injection (IVF-ICSI) treatment?Summary Answer: Microbiome profiling with the use of interspace profiling (IS-pro) technique enables stratification of the chance of becoming pregnant prior to the start of an IVF or IVF-ICSI treatment.What Is Known Already: Live-birth rates for an IVF or IVF-ICSI treatment vary between 25 and 35% per cycle and it is difficult to predict who will or will not get pregnant after embryo transfer (ET). Recently, it was suggested that the composition of the vaginal microbiota prior to treatment might predict pregnancy outcome. Analysis of the vaginal microbiome prior to treatment might, therefore, offer an opportunity to improve the success rate of IVF or IVF-ICSI.Study Design, Size, Duration: In a prospective cohort study, 303 women (age, 20-42 years) undergoing IVF or IVF-ICSI treatment in the Netherlands were included between June 2015 and March 2016.Participants/materials, Setting, Methods: Study subjects provided a vaginal sample before the start of the IVF or IVF-ICSI procedure. The vaginal microbiota composition was determined using the IS-pro technique. IS-pro is a eubacterial technique based on the detection and categorization of the length of the 16S-23S rRNA gene interspace region. Microbiome profiles were assigned to community state types based on the dominant bacterial species. The predictive accuracy of the microbiome profiles for IVF and IVF-ICSI outcome of fresh ET was evaluated by a combined prediction model based on a small number of bacterial species. From this cohort, a model was built to predict outcome of fertility treatment. This model was externally validated in a cohort of 50 women who were undergoing IVF or IVF-ICSI treatment between March 2018 and May 2018 in the Dutch division of the MVZ VivaNeo Kinderwunschzentrum Düsseldorf, Germany.Main Results and the Role Of Chance: In total, the vaginal microbiota of 192 women who underwent a fresh ET could be analysed. Women with a low percentage of Lactobacillus in their vaginal sample were less likely to have a successful embryo implantation. The prediction model identified a subgroup of women (17.7%, n = 34) who had a low chance to become pregnant following fresh ET. This failure was correctly predicted in 32 out of 34 women based on the vaginal microbiota composition, resulting in a predictive accuracy of 94% (sensitivity, 26%; specificity, 97%). Additionally, the degree of dominance of Lactobacillus crispatus was an important factor in predicting pregnancy. Women who had a favourable profile as well as <60% L. crispatus had a high chance of pregnancy: more than half of these women (50 out of 95) became pregnant. In the external validation cohort, none of the women who had a negative prediction (low chance of pregnancy) became pregnant.Limitations, Reasons For Caution: Because our study uses a well-defined study population, the results will be limited to the IVF or IVF-ICSI population. Whether these results can be extrapolated to the general population trying to achieve pregnancy without ART cannot be determined from these data.Wider Implications Of the Findings: Our results indicate that vaginal microbiome profiling using the IS-pro technique enables stratification of the chance of becoming pregnant prior to the start of an IVF or IVF-ICSI treatment. Knowledge of their vaginal microbiota may enable couples to make a more balanced decision regarding timing and continuation of their IVF or IVF-ICSI treatment cycles.Study Funding/competing Interest(s): This study was financed by NGI Pre-Seed 2014-2016, RedMedTech Discovery Fund 2014-2017, STW Valorisation grant 1 2014-2015, STW Take-off early phase trajectory 2015-2016 and Eurostars VALBIOME grant (reference number: 8884). The employer of W.J.S.S.C. has in collaboration with ARTPred acquired a MIND subsidy to cover part of the costs of this collaboration project. The following grants are received but not used to finance this study: grants from Innovatie Prestatie Contract, MIT Haalbaarheid, other from Dutch R&D tax credit WBSO, RedMedTech Discovery Fund, (J.D.d.J.). Grants from Ferring (J.S.E.L., K.F., C.B.L. and J.M.J.S.S.), Merck Serono (K.F. and C.B.L.), Dutch Heart Foundation (J.S.E.L.), Metagenics Inc. (J.S.E.L.), GoodLife (K.F.), Guerbet (C.B.L.). R.K. is employed by ARTPred B.V. during her PhD at Erasmus Medical Centre (MC). S.A.M. has a 100% University appointment. I.S.P.H.M.S., S.A.M. and A.E.B. are co-owners of IS-Diagnostics Ltd. J.D.d.J. is co-owner of ARTPred B.V., from which he reports personal fees. P.H.M.S. reports non-financial support from ARTPred B.V. P.H.M.S., J.D.d.J. and A.E.B. have obtained patents `Microbial population analysis' (9506109) and `Microbial population analysis' (20170159108), both licenced to ARTPred B.V. J.D.d.J. and A.E.B. report patent applications `Method and kit for predicting the outcome of an assisted reproductive technology procedure' (392EPP0) and patent `Method and kit for altering the outcome of an assisted reproductive technology procedure' by ARTPred. W.J.S.S.C. received personal consultancy and educational fees from Goodlife Fertility B.V. J.S.E.L. reports personal consultancy fees from ARTPred B.V., Titus Health B.V., Danone, Euroscreen and Roche during the conduct of the study. J.S.E.L. and N.G.M.B. are co-applicants on an Erasmus MC patent (New method and kit for prediction success of in vitro fertilization) licenced to ARTPred B.V. F.J.M.B. reports personal fees from Advisory Board Ferring, Advisory Board Merck Serono, Advisory Board Gedeon Richter and personal fees from Educational activities for Ferring, outside the submitted work. K.F. reports personal fees from Ferring (commercial sponsor) and personal fees from GoodLife (commercial sponsor). C.B.L. received speakers' fee from Ferring. J.M.J.S.S. reports personal fees and other from Merck Serono and personal fees from Ferring, unrelated to the submitted paper. The other authors declare that they have no competing interests.Trial Registration Number: ISRCTN83157250. Registered 17 August 2018. Retrospectively registered. [ABSTRACT FROM AUTHOR]

Study Question: Is there an association between maternal occupational exposure to solvents, pesticides and metals as assessed by expert-based assessment and congenital anomalies in the offspring?Summary Answer: There is an association between maternal occupational exposure to solvents and congenital anomalies in the offspring, including neural tube defects, congenital heart defects and orofacial clefts.What Is Known Already: One important environmental risk factor for development of congenital anomalies is maternal occupational exposure to chemicals in the workplace prior to and during pregnancy. A number of studies have assessed the association with often conflicting results, possibly due to different occupational exposure assessing methods.Study Design, Size, Duration: For this systematic review with meta-analysis, the search terms included maternal occupation, exposure, congenital anomalies and offspring. Electronic databases MEDLINE and EMBASE were searched for English studies up to October 2017.Participants/materials, Setting, Methods: Two reviewers independently screened all citations identified by the search. Case-control studies and cohort studies were included if (I) they reported on the association between maternal occupational exposure to solvents, pesticides or metals and congenital anomalies, and (II) assessment of occupational exposure was performed by experts. Data on study characteristics, confounders and odds ratios (ORs) were extracted from the included studies for four subgroups of congenital anomalies. Methodological quality was assessed using the Newcastle-Ottawa Scale. In the meta-analysis, random effects models were used to pool estimates.Main Results and the Role Of Chance: In total, 2806 titles and abstracts and 176 full text papers were screened. Finally, 28 studies met the selection criteria, and 27 studies could be included in the meta-analysis. Our meta-analysis showed that maternal occupational exposure to solvents was associated with neural tube defects (OR: 1.51, 95%CI: 1.09-2.09) and congenital heart defects (OR: 1.31, 95%CI:1.06-1.63) in the offspring. Also maternal occupational exposure to glycol ethers, a subgroup of solvents, was associated with neural tube defects (OR: 1.93, 95%CI: 1.17-3.18) and orofacial clefts (OR: 1.95, 95%CI: 1.38-2.75) in the offspring. Only one study investigated the association between maternal occupational exposure to solvents and hypospadias and found an association (OR: 3.63, 95%CI: 1.94-7.17). Results of the included studies were consistent. In our meta-analysis, we found no associations between occupational exposure to pesticides or metals and congenital anomalies in the offspring.Limitations, Reasons For Caution: A limited number of studies was included, which made it impossible to calculate pooled estimates for all congenital anomalies, analyse individual chemicals or calculate exposure-response relations. Bias could have been introduced because not all included studies corrected for potentially confounding factors.Wider Implications Of the Findings: Employers and female employees should be aware of the possible teratogenic effects of solvent exposure at the workplace. Therefore, is it important that clinicians and occupational health specialist provide women with preconception advice on occupational solvent exposure, to reduce the congenital anomaly risk.Study Funding/competing Interest(s): NSp was paid by the Graduate School of Medical Sciences (MD/PhD program), UMCG, Groningen, the Netherlands. EUROCAT Northern Netherlands is funded by the Dutch Ministry of Health, Welfare and Sports. There are no competing interests.Registration Number: CRD42017053943. [ABSTRACT FROM AUTHOR]

Study Question: Is anogenital distance (AGD) associated with semen quality and reproductive hormones in men from the general population?Summary Answer: Short AGD measured from the anus to the base of scrotum (AGDAS) was associated with reduced sperm counts and morphology but not with sperm motility or reproductive hormones.What Is Known Already: AGD is longer in males than in females. In rodents, AGD is a well-established and sensitive marker of disruption during the masculinization programming window in utero and it has been suggested to be so in humans as well. Therefore, the average AGD would be expected to be shorter in men with poor semen quality, which some studies have confirmed while others have not.Study Design, Size, Duration: This cross-sectional population-based study was of 1106 men included between 2012 and 2016.Participants/materials, Setting, Methods: Men from the general Danish population (median age 19 years), unselected with regard to fertility status and semen quality, delivered a semen sample, had a blood sample drawn, which was analyzed for concentrations of reproductive hormones, and answered a comprehensive questionnaire. They also had a physical examination performed including determination of AGD measured as the distance between anus and scrotum (AGDAS) and penis (AGDAP). Odds ratios (OR) and 95% CI were estimated for a man having abnormal semen parameters according to the World Health Organization's reference values or a low/high concentration of reproductive hormones (defined as the lowest or highest 10%) depending on AGD. AGD was categorized in four strata: ≤10th percentile, 10th-30th percentile, 30th-50th percentile and >50th percentile.Main Results and the Role Of Chance: Men with the 10% shortest AGDAS had a more than doubled risk (OR: 2.19, 95% CI: 1.40-3.42) of being in the subfertile range for either sperm concentration (<15 million/mL) or sperm morphology (<4%) compared to men with AGDAS above the median (reference). Men in the 10th-30th percentile also had an increased OR of 1.48 (95% CI: 1.06-2.08) but not men in the 30th-50th percentile (OR: 1.14, 95% CI: 0.81-1.62). AGDAP was only weakly related to semen quality. AGD was not associated with testicular volume or any of the reproductive hormones.Limitations, Reasons For Caution: Limitations include the potential non-differential misclassification of reproductive outcomes based on a single semen and blood sample and some between-examiner differences in AGD measurements which introduces noise and may result in an underestimation of observed associations.Wider Implications Of the Findings: Our study of men from the general population confirmed associations between AGD and semen quality, supporting the hypothesis that AGD in humans could be a marker of fetal testicular development. This suggests that the low semen quality in Danish men may partly be explained by prenatal factors.Study Funding/competing Interest(s): The study has received financial support from the ReproUnion (L.P.); the Research fund of Rigshospitalet, Copenhagen University Hospital (N.J.); Grants R01ES016863-04 and R01ES016863-02S4; National Institute of Environmental Health Sciences (NIEHS) and National Institute of Environmental Health Sciences grant (P30ES023515) (S.S.); the European Union (Contract numbers BMH4-CT96-0314, QLK4-CT-1999-01422, QLK4-CT-2002-00603, FP7/2007-2013, DEER Grant agreement no. 212844); the Danish Ministry of Health; the Danish Environmental Protection Agency; A.P. Møller and wife Chastine McKinney Møllers foundation; and Svend Andersens Foundation. None of the funders had any role in the study design, collection, analysis or interpretation of data, writing of the paper or publication decisions. The authors have nothing to declare.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

Study Question: Does pre-treatment with a low dose of mifepristone improve irregular vaginal bleeding patterns during the initial 3 months after LNG-IUS placement?Summary Answer: Mifepristone treatment prior to LNG-IUS insertion results in significantly lower bleeding and spotting rates but no significant reduction post insertion.What Is Known Already: One of the leading causes of premature discontinuation of the LNG-IUS is unscheduled bleeding in the first months following its insertion. Up to now, there has been no effective treatment to prevent this side effect which reduces continuation rates for one of the most effective contraceptives.Study Design, Size, Duration: This randomized, double blinded, controlled trial was conducted between 2009 and 2015. In total, 68 women opting for a LNG-IUS were screened for eligibility, of whom 58 were randomized at a ratio of 1:1 in blocks of 10 to pre-treatment with mifepristone or a comparator. The main outcome was the rate of bleeding and spotting days reported during the first 3 months post LNG-IUS 52 mg placement.Participants/materials, Setting, Methods: Healthy women with regular and normal menstrual cycles aged 18-43 years were enrolled at a single center in a university hospital; 29 were allocated to 2 months pre-treatment with a low dose mifepristone and 29 to the comparator prior to insertion of the LNG-IUS. Women were advised to use barrier methods during the pre-treatment period. Bleeding diaries were collected for the pre-treatment period and for the first 6 months after the LNG-IUS placement.Main Results and the Role Of Chance: There were no differences in demographics or baseline characteristics between the study groups. Data for analysis of the main outcome were contributed by a per protocol population of 19 women per group. There was a significant lower bleeding and spotting rate in the mifepristone group (-17.8% points, P < 0.001) after 2 months of pretreatment but after the LNG-IUS insertion no significant difference could be seen. While no pregnancies occurred prior to LNG-IUS insertion in the mifepristone group, there were three unintended pregnancies in the comparator group which emphasizes the need for a reliable contraceptive potential in any pre-treatment regiment used in clinical practice.Limitations, Reasons For Caution: The use of mifepristone prior to the LNG-IUS insertion in this trial was used as prophylaxis against unscheduled bleeding after the placement of the device. Although this side effect constitutes a major concern in a clinical setting, only a subset of women are at risk. This is the first study using pre-treatment to attempt improved bleeding control. The differences were small and the effect was short lasting but the reduced rate of bleeding and spotting observed during the first month following LNG-IUS insertion, even though not statistically significant, indicates that this approach may be further explored. The fact that there were three pregnancies in the comparator group stresses the need for any pre-treatment to also protect against unplanned pregnancy.Wider Implications Of the Findings: Modified treatment protocols of mifepristone could be used prior to the LNG-IUS insertion to investigate possible further improvement of the outcome. The effect size of the current dose used might have been more prominent in women with LNG-IUS if the treatment also continued some weeks after the placement of the device. Although the low dose of mifepristone used in this trial is not available in Europe, other progesterone receptor modulators currently available could be investigated in larger clinical trials. To avoid unintended pregnancy in the pretreatment period, the dosage used should, ideally, also be effective for contraception and the pretreatment period should be kept as short as possible.Study Funding/competing Interest(s): This study was funded by the Swedish Research Council (2012-2844, 2017-00932), Stockholm County Council and Karolinska Institutet (ALF). Conflicts of interests for K.G.D. and H.K.K. are listed at the end of the paper. The other authors have no conflicts of interest.Trial Registration Number: EudraCT number 2009-009014-40. Regional ethical review board at Karolinska Institutet permit 2009/144-31/4.Trial Registration Date: 20 July 2009.Date Of First Patient’s Enrolment: 24 November 2009. [ABSTRACT FROM AUTHOR]

Study Question: What are the reasons for or against the future clinical application of germline genome modification (GGM)?Summary Answer: A total of 169 reasons were identified, including 90 reasons for and 79 reasons against future clinical application of GGM.What Is Known Already: GGM is still unsafe and insufficiently effective for clinical purposes. However, the progress made using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)- CRISPR-associated system (Cas) has led scientists to expect to overcome the technical hurdles in the foreseeable future. This has invited a debate on the socio-ethical and legal implications and acceptability of clinical applications of GGM. However, an overview of the reasons presented in this debate is missing.Study Design, Size, Duration: MEDLINE was systematically searched for articles published between January 2011 and June 2016. Articles covering reasons for or against clinical application of intentional modification of the nuclear DNA of the germline were included.Participants/materials, Setting, Methods: Two researchers independently extracted the reported reasons from the articles and grouped them into categories through content analysis.Main Results and the Role Of Chance: The systematic search yielded 1179 articles and 180 articles were included. Most papers were written by professionals in ethics, (science) journalism and biomedical sciences. Overall, 169 reasons were identified, including 90 reasons for, and 79 reasons against future clinical application of GGM. None of the included articles mentioned more than 60/169 reasons. The reasons could be categorized into: (i) quality of life of affected individuals; (ii) safety; (iii) effectiveness; (iv) existence of a clinical need or alternative; (v) costs; (vi) homo sapiens as a species (i.e. relating to effects on our species); (vii) social justice; (viii) potential for misuse; (ix) special interests exercising influence; (x) parental rights and duties; (xi) comparability to acceptable processes; (xii) rights of the unborn child; and (xiii) human life and dignity. Considerations relating to the implementation processes and regulation were reported.Limitations, Reasons For Caution: We cannot ensure completeness as reasons may have been omitted in the reviewed literature and our search was limited to MEDLINE and a 5-year time period.Wider Implications Of the Findings: Besides needing (pre)clinical studies on safety and effectiveness, authors call for a sound pre-implementation process. This overview of reasons may assist a thorough evaluation of the responsible introduction of GGM.Study Funding/competing Interest(s): University of Amsterdam, Alliance Grant of the Amsterdam Reproduction and Development Research Institute (I.D.), and Clinical Center, Department of Bioethics, National Institutes of Health Intramural Research Program (S.H.). There are no competing interests. [ABSTRACT FROM AUTHOR]

Endometrial scratching or injury was first suggested a decade ago as a simple intervention to improve endometrial receptivity in patients undergoing ART. More than a decade later, based on weak evidence some doctors have adopted this strategy, although there is not yet agreement about its real benefit. In this opinion paper, we analyze the methodological and plausibility problem beneath ‘the Scratching Case’. This is also applicable to several other examples of spurious associations reported in the literature. In particular, we emphasize what should be done so as not to dilute evidence-based medicine by a vicious circle created by the over-exploitation of inadequate or insufficient data to compute incorrect or incomplete conclusions. [ABSTRACT FROM PUBLISHER]

Freezing of ovarian tissue for fertility preservation has been gaining ground as a valid method in recent years. More than 100 children have been born from this procedure worldwide. As a result, many fertility clinics are now implementing this method. However, the practical procedures that need to be mastered to successfully implement the freezing of ovarian tissue are different in many aspects from those normally used in fertility clinics and are not well defined. Furthermore, success is difficult to measure since patients usually do not return for transplantation until several years after freezing, which puts extra emphasis of good quality control and quality assurance measures to secure a transplantation of tissue with surviving follicles that can sustain fertility. The present paper describes the procedures and a checklist implemented in Denmark in order to secure a successful clinical service. To standardize and implement uniform measures for this new method, we suggest a consensus conference to collectively agree on the best technical and clinical practice. [ABSTRACT FROM AUTHOR]

Study Question: How are temporal trends in lifestyle factors, including exposure to maternal smoking in utero, associated to semen quality in young men from the general population?Summary Answer: Exposure to maternal smoking was associated with lower sperm counts but no overall increase in sperm counts was observed during the study period despite a decrease in this exposure.What Is Known Already: Meta-analyses suggest a continuous decline in semen quality but few studies have investigated temporal trends in unselected populations recruited and analysed with the same protocol over a long period and none have studied simultaneous trends in lifestyle factors.Study Design, Size, Duration: Cross-sectional population-based study including ~300 participants per year (total number = 6386) between 1996 and 2016.Participants/materials, Setting, Methods: The study is based on men from the Greater Copenhagen area, Denmark, with a median age of 19 years, and unselected with regard to fertility status and semen quality. The men delivered a semen sample, had a blood sample drawn and a physical examination performed and answered a comprehensive questionnaire, including information on lifestyle and the mother's pregnancy. Temporal trends in semen quality and lifestyle were illustrated graphically, and trends in semen parameters and the impact of prenatal and current lifestyle factors were explored in multiple regression analyses.Main Results and the Role Of Chance: Throughout the study period, 35% of the men had low semen quality. Overall, there were no persistent temporal trends in semen quality, testicular volume or levels of follicle-stimulating hormone over the 21 years studied. The men's alcohol intake was lowest between 2011 and 2016, whereas BMI, use of medication and smoking showed no clear temporal trends. Parental age increased, and exposure in utero to maternal smoking declined from 40% among men investigated in 1996-2000 to 18% among men investigated in 2011-2016. Exposure to maternal smoking was associated with lower sperm counts but no overall increase in sperm counts was observed despite the decrease in this exposure.Limitations, Reasons For Caution: Information of current and prenatal lifestyle was obtained by self-report, and the men delivered only one semen sample each.Wider Implications Of the Findings: The significant decline in in utero exposure to maternal smoking, which was not reflected in an overall improvement of semen quality at the population level, suggest that other unknown adverse factors may maintain the low semen quality among Danish men.Study Funding/competing Interest(s): The study has received financial support from the ReproUnion; the Research fund of Rigshospitalet, Copenhagen University Hospital; the European Union (Contract numbers BMH4-CT96-0314,QLK4-CT-1999-01422, QLK4-CT-2002-00603, FP7/2007-2013, DEER Grant agreement no. 212844); the Danish Ministry of Health; the Danish Environmental Protection Agency; A.P. Møller and wife Chastine McKinney Møllers foundation; and Svend Andersens Foundation. None of the funders had any role in the study design, collection, analysis or interpretation of data, writing of the paper or publication decisions.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]