P-425 Effect of time interval between SARS-COV-2 infection and frozen-thawed embryo transfer on pregnancy outcomes
Authors: Lu Y , Huang J , He Y , Lindheim S , Wei Z , Sun Y 
Published: July 2024

Abstract

Study question
Does the time interval between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and frozen-thawed embryo transfer (FET) affect pregnancy outcomes?

Summary answer
Delaying the subsequent FET for at least 30 days after the SARS-COV-2 infection was associated with beneficial pregnancy outcomes.

What is known already
Coronavirus disease 2019 (COVID-19), as a multi-systemic disease, poses a threat to reproductive health. Despite reassuring studies have shown that SARS-CoV-2 infection does not appear to affect human oocytes and embryos in fresh cycles, there is limited data regarding the effects of SARS-CoV-2 infection on FET outcomes.Particularly, it remains unclear whether it is beneficial to postpone embryo transfer after SARS-COV-2 infection.

Study design, size, duration
Retrospective cohort study, including 2165 FET cycles between November 2022 and May 2023 from an academic fertility center.

Participants/materials, setting, methods

Participants
The infected group: Patients who were infected with SARS-CoV-2 before FET. According to the different time interval from the day of infection to embryo transfer, these cycles were further categorized into four subgroups: ≤30 days, 31-60 days, 61-90 days, and ≥91 days.
The non-infected group: Patients undergoing FET during the same period who were asymptomatic and tested negative.
Outcome measures: rates of biochemical pregnancy (BPR), clinical pregnancy (CPR), early pregnancy loss (EPLR) and ongoing pregnancy (OPR).

Main results and the role of chance
A total of 997 FET cycles were included in the non-infected (32.9±3.9 years) and 1168 in the infected groups (32.7±4.1 years), among which, 82(7.0%), 212(18.2%), 471(40.3%) and 403(34.5%) were infected ≤30, 31-60, 61-90, and ≥91 days before FET, respectively.
Overall, no differences were observed across the ≤30, 31-60, 61-90, ≥91 days’ subgroup and the non-infected group with respect to BPR (53.7%, 64.6%, 63.7%, 62.3%, and 66.6%, p = 0.129), CPR (46.3%, 54.7%, 56.3%, 54.6%, and 57.4%, p = 0.362), EPLR (29.5%, 24.8%, 23.3%, 22.3%, and 21.5%, p = 0.712) and OPR (37.8%, 47.2%, 48.6%, 48.1%, and 51.5%, p = 0.143). Although non-significant, a reduction in BPR, CPR and OPR was noted in those with SARS-CoV-2 infection ≤30 days before FET.
Generalized estimating equations logistic regression models were applied to investigate if there’s any association between pregnancy outcomes and time interval from infection to FET while adjusting for potential confounders. Results revealed that SARS-CoV-2 infection within 30 days prior to FET was associated significantly reduced odds of biochemical pregnancy (adjusted odds ratio [aOR] 0.50, 95% confidence interval [CI] 0.31-0.80), clinical pregnancy (aOR 0.57, 95%CI 0.36-0.90) and ongoing pregnancy (aOR 0.52, 95%CI 0.32-0.84) compared to the non-infected group, while no such associations were observed with infection &gt;30 days before FET.

Limitations, reasons for caution
The retrospective nature of the study and limited sample size in the ≤30 days’ subgroup limits the generalizability of the findings. Large-scale prospective studies are warranted to verify our results.

Wider implications of the findings
Our findings suggest that while overall, SARS-COV-2 infection has no adverse impact on pregnancy outcomes, delaying an embryo transfer for at least 30 days after an infection may be more beneficial for FET cycles.

Trial registration number
Not applicable.