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Background: The trend of increasing caesarean section (CS) rates brings up questions related to subfertility. Research regarding the influence of CS on assisted reproduction techniques (ART) is conflicting. A potential mechanism behind CS-induced subfertility is intra uterine fluid resulting from a caesarean scar defect or niche. The vaginal microbiome has been repeatedly connected to negative ART outcomes, but it is unknown if the microbiome is changed in relation to a niche. Methods: This systematic review describes literature investigating the effect of a niche on live birth rates after assisted reproduction. Furthermore, studies investigating a difference in microbial composition in subfertile persons with a niche compared to no niche are evaluated. Pubmed, Embase and Web of Science were searched on March 2023 for comparative studies on both study questions. Inclusion criteria were i.e., English language, human-only studies, availability of the full article and presence of comparative pregnancy data on a niche. The quality of the included studies and their risk of bias were assessed using the Newcastle-Ottawa scale for cohort studies. The results were graphically displayed in a forest plot. Results: Six retrospective cohort studies could be included on fertility outcomes, with a total of 1083 persons with a niche and 3987 without a niche. The overall direction of effect shows a negative impact of a niche on the live birth rate (pooled aOR 0.58, 95% CI 0.48-0.69) with low-grade evidence. Three studies comparing the microbiome between persons with and without a CS could be identified. Conclusion: There is low-grade evidence to conclude that the presence of a niche reduces live birth rates when compared to persons without a niche. The theory that a caesarean has a negative impact on pregnancy outcomes because of dysbiosis promoted by the niche is interesting, but there is no sufficient literature about this. PLAIN LANGUAGE SUMMARY: The increasing number of caesarean deliveries has raised concerns about how it might affect a woman's ability to get pregnant afterwards. Some studies suggest that having a caesarean section (CS) could make it harder to conceive, particularly through in vitro fertilisation (IVF). The reason could be the scar or niche from a previous caesarean. This niche can cause fluid inside the uterus. We also know that the mix of bacteria in the vagina, called the vaginal microbiome, can affect a woman's chances of getting pregnant, especially with treatments like IVF. But we are not sure if having a caesarean affects the vaginal microbiome. To understand this better, van den Tweel's team looked at studies on whether having a niche from a caesarean affects a woman's chance of having a baby through IVF. They also looked at studies comparing the bacteria in the vagina of women who have had a caesarean with those who have not. They found that having a caesarean niche makes it harder for a woman to have a baby through IVF. However, the evidence from these studies is not very strong. We still do not know enough about whether having a caesarean niche affects the bacteria in the vagina. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the influence of bacterial vaginosis on time to pregnancy in subfertile couples., Methods: Couples attending a teaching hospital in the Netherlands having an initial fertility assessment (IFA) between July 2019 and June 2022 were included in this prospective study, with follow-up of pregnancies until June 2023. Vaginal samples at IFA were analyzed on pH, qPCR BV, and 16S rRNA gene microbiome analysis of V1-V2 region. Main outcome measures were time from initial fertility assessment to ongoing pregnancy at 12 weeks and live birth, analyzed by Kaplan-Meier and Cox regression with adjustment for potential confounders., Results: At IFA, 27% of 163 included participants tested positive for BV. BV status had no influence on time to ongoing pregnancy (HR 0.98, 0.60-1.61, aHR 0.97, 0.58-1.62). In persons with unexplained subfertility, positive BV status had a tendency of longer time to pregnancy. When persons had an indication for fertility treatment, positive BV status (HR 0.21, 0.05-0.88, aHR 0.19, 0.04-0.85) and microbiome community state type III and type IV had significant longer time to pregnancy., Conclusion: This study indicates that BV may have a potential negative impact on time to live birth pregnancy in subfertile persons with an indication for fertility treatment. This study did not find an association between BV and time to live birth pregnancy in a general group of subfertile couples or in unexplained subfertility. More research should be done in persons with unexplained subfertility and if treatment improves time to pregnancy., (© 2024. The Author(s).)

This study aimed to investigate the influence of hormonal treatment on the vaginal microbiome during fertility treatments. Bacterial vaginosis (BV) could affect fecundity, particularly in the in vitro fertilization (IVF) population, where negative effects on pregnancy outcomes have been reported. It is hypothesized that the hormone treatment during fertility treatments could influence the abundance of Lactobacilli, with negative effects on the pregnancy results. A total of 53 couples attending a fertility clinic in the Netherlands between July 2019 and August 2022 were included in this prospective cohort study. Vaginal samples were collected at start of treatment, oocyte retrieval or insemination from subjects undergoing intra uterine insemination (IUI) with mild ovarian stimulation, and IVF or intra cytoplasmatic sperm injection (ICSI) with controlled ovarian hyperstimulation. AmpliSens® Florocenosis/Bacterial vaginosis-FRT qPCR and 16S rRNA gene-based amplicon sequencing were performed on all samples. In total, 140 swabs were analyzed, with a median of two swabs per person. 33 (24%) tested qPCR BV positive. Lactobacilli percentage decreased during fertility treatments, leading to changes in the vaginal microbiome. Shannon diversity index was not significantly different. Of the total of 53 persons, nine switched from qPCR BV negative to positive during treatment. The persons switching to qPCR BV positive had already a (not significant) higher Shannon diversity index at start of treatment. If the vaginal microbiome of persons deteriorates during fertility treatments, timing of following treatments, lifestyle modifications, or a freeze all strategy could be of possible benefit., (© 2024. The Author(s).)

In 2003, in the context of a national research funding program in which obstetric research was prioritized, several perinatal centers took the initiative to jointly submit a number of applications to the subsidy programs of Effectiveness Research and Prevention of ZonMw. This has led to the funding of the Obstetric Consortium with several projects, including the "Hypertension in Pregnancy Intervention Trial At Term" and the "Disproportionate Intrauterine Growth Intervention Trial At Term" studies. The studies showed that induction of labor for hypertension and growth restriction at term was the appropriate management. Subsequent implementation improved maternal and perinatal outcomes., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: Pregnancy hypertension is a leading cause of maternal and perinatal mortality and morbidity. Between 34 +0 and 36 +6 weeks gestation, it is uncertain whether planned delivery could reduce maternal complications without serious neonatal consequences. In this individual participant data meta-analysis, we aimed to compare planned delivery to expectant management, focusing specifically on women with preeclampsia., Data Sources: We performed an electronic database search using a prespecified search strategy, including trials published between January 1, 2000 and December 18, 2021. We sought individual participant-level data from all eligible trials., Study Eligibility Criteria: We included women with singleton or multifetal pregnancies with preeclampsia from 34 weeks gestation onward., Methods: The primary maternal outcome was a composite of maternal mortality or morbidity. The primary perinatal outcome was a composite of perinatal mortality or morbidity. We analyzed all the available data for each prespecified outcome on an intention-to-treat basis. For primary individual patient data analyses, we used a 1-stage fixed effects model., Results: We included 1790 participants from 6 trials in our analysis. Planned delivery from 34 weeks gestation onward significantly reduced the risk of maternal morbidity (2.6% vs 4.4%; adjusted risk ratio, 0.59; 95% confidence interval, 0.36-0.98) compared with expectant management. The primary composite perinatal outcome was increased by planned delivery (20.9% vs 17.1%; adjusted risk ratio, 1.22; 95% confidence interval, 1.01-1.47), driven by short-term neonatal respiratory morbidity. However, infants in the expectant management group were more likely to be born small for gestational age (7.8% vs 10.6%; risk ratio, 0.74; 95% confidence interval, 0.55-0.99)., Conclusion: Planned early delivery in women with late preterm preeclampsia provides clear maternal benefits and may reduce the risk of the infant being born small for gestational age, with a possible increase in short-term neonatal respiratory morbidity. The potential benefits and risks of prolonging a pregnancy complicated by preeclampsia should be discussed with women as part of a shared decision-making process., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)