Biochemical or clinical pregnancy loss after first embryo transfer does not affect subsequent transfer outcome

Abstract

Research question: Does biochemical or clinical pregnancy loss after frozen embryo transfer (FET) increase the odds of pregnancy loss in a subsequent transfer? Design: Retrospective cohort study evaluating patients who underwent two consecutive single FETs using either euploid or untested embryos at a university-affiliated fertility centre between January 2017 and December 2021. Patients who had experienced a biochemical or clinical pregnancy loss after the first FET were compared with those who had experienced implantation failure in the subsequent FET. Results: Among 2103 patients who underwent two consecutive euploid FETs, those who had experienced a biochemical loss after their first euploid FET had a subsequent biochemical loss rate of 9.9% and a clinical loss rate of 10.5% in their second euploid FET. These rates did not significantly differ from those who had experienced previous implantation failure (9.6%, P = 0.89010.9%, P = 0.556, respectively). Similarly, among patients who had experienced a clinical loss in their first euploid FET, rates of biochemical and clinical loss in the second euploid transfer were comparable to those who had experienced previous implantation failure (11.5% versus 9.6%, P = 0.272and 12.5% versus 10.9%, P = 0.456, respectively). These findings remained consistent when analysing untested (n = 282) FETs, with no significant differences in subsequent pregnancy loss rates between patients who had experienced previous pregnancy loss and those who had experienced implantation failure. Conclusions: Biochemical or clinical pregnancy loss after a euploid or untested FET is not associated with an increased risk of pregnancy loss in the subsequent transfer.