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

Does biochemical or clinical pregnancy loss after frozen embryo transfer (FET) increase the odds of pregnancy loss in a subsequent transfer?

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.

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 = 0.890; 10.9%, 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 = 0.272; and 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.

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.