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To investigate whether endometrial thickness (ET) independently affects the live birth rate (LBR) after embryo transfer. Retrospective study. Private assisted reproductive technology center. A total of 959 single euploid frozen embryo transfers. Vitrified euploid blastocyst transfer. Live birth rate per embryo transfer. The conditional density plots did not demonstrate either a linear relationship between the ET and LBR or a threshold below which the LBR decreased perceivably. Receiver operating characteristic curve analyses did not suggest a predictive value of the ET for the LBR. The area under the curve values were 0.55, 0.54, and 0.54 in the overall, programmed, and natural cycle transfers, respectively. Logistic regression analyses with age, embryo quality, day of trophectoderm biopsy, body mass index, and ET did not suggest an independent effect of the ET on the LBR. We did not identify a threshold of the ET that either precluded live birth or under which the LBR decreases perceivably. Common practice of cancelling embryo transfers when the ET is <7 mm may not be justified. Prospective studies, in which the management of the transfer cycle would not be altered by ET, would provide higher-quality evidence on the subject. [ABSTRACT FROM AUTHOR]

Objective: To present a definition of recurrent implantation failure that accounts for the effects of female age and anticipated blastocyst euploidy rates on cumulative implantation rates.Design: Mathematical modeling.Setting: Not applicable.Patient(s): Not applicable.Intervention(s): Mathematical modeling of cumulative implantation probability on the basis of published blastocyst euploidy rates across categories of female age.Main Outcome Measure(s): The number of blastocysts required to achieve 95% cumulative implantation probability under the assumption of the absence of any other factor affecting implantation.Result(s): When the euploidy status of the transferred embryo is unknown (i.e., not subjected to preimplantation genetic testing for aneuploidies), our simulation shows that no age category reaches 95% cumulative probability of implantation of at least one embryo until after transfer of seven blastocysts. The number of blastocysts required to reach the same threshold is higher for older patients. For example, women older than 38 years require transfer of more than 10 untested blastocysts for the upper range of predictive probability to meet the threshold of 95%. On the other hand, if the implantation rate for a euploid blastocyst is assumed to be 55%, then 4 blastocysts are enough to reach a cumulative probability rate greater than 95%, regardless of age.Conclusion(s): The term "recurrent implantation failure" should be a functional term guiding further management. We suggest that recurrent implantation failure should not be called until implantation failure becomes reasonably likely to be caused by factors other than embryo aneuploidy, the leading cause of implantation failure. We propose a new definition that factors in anticipated blastocyst euploidy rates across categories of female age, euploid blastocyst implantation rate, and a specified threshold of cumulative probability of implantation. [ABSTRACT FROM AUTHOR]

To date, recurrent implantation failure (RIF) has no clear definition and no clearly identified impaired function. Hence, the term RIF is currently used somewhat haphazardly, on the basis of clinicians' judgment. International experts in reproductive medicine met on July 1, 2022, in Lugano, Switzerland, to review the different facets of RIF and define the diagnosis and its appropriate management. A systematic review without meta-analysis of studies published in English from January 2015 to May 2022. Data indicated that RIF has been largely overevaluated, overdiagnosed, and overtreated without sufficient critical assessment of its true nature. Our analyses show that true RIF is extremely uncommon—occurring in <5% of couples with infertility—and that reassurance and continued conventional therapies are warranted in most cases of assisted reproductive technology (ART) failure. Although the true biologic determinants of RIF may exist in a small subset of people with infertility, they elude the currently available tools for assessment. Without identification of the true underlying etiology(ies), it is reasonable not to assign this diagnosis to a patient until she has failed at least 3 euploid blastocyst transfers (or the equivalent number of unscreened embryo transfers, adjusted to the patient's age and corresponding euploidy rate). In addition, other factors should be ruled out that may contribute to her reduced odds of sustained implantation. In such cases, implantation failure should not be the only issue considered in case of ART failure because this may result from multiple other factors that are not necessarily repetitive or persistent. In reality, RIF impacting the probability of further ART success is a very rare occurrence. True RIF is extremely uncommon, occurring in <5% of couples with infertility. Reassurance and continued conventional therapies are warranted in most cases. It would seem reasonable not to assign this diagnosis to a patient until she has failed at least 3 euploid embryo transfers (or the equivalent number of unscreened embryos, adjusted to her age). Given the number of internationally recognized experts in the field present at the Lugano meeting 2022, our publication constitutes a consensus statement. [ABSTRACT FROM AUTHOR]