Abstract
PURPOSE: To evaluate whether prior SARS-CoV-2 infection adversely affects live birth and perinatal outcomes following subsequent frozen-thawed embryo transfer (FET) and to further investigate whether the time interval between infection and embryo transfer influences pregnancy outcomes. METHODS: In this retrospective cohort study, women who tested positive for SARS-CoV-2 before FET were designated as the infected group (n = 1081), while asymptomatic and test-negative women were included as controls (n = 865). The infected group was further subdivided into four subgroups according to the time interval from infection to FET: ≤ 30, 31-60, 61-90, and ≥ 91 days. RESULTS: Overall, positive HCG rate was significantly lower in the infected group compared to the non-infected group (62.9% vs. 67.5%, adjusted OR = 0.80, 95% CI = 0.66-0.97, P = 0.021), while no significant differences were observed in live birth rates (45.9% vs. 49.7%, adjusted OR = 0.84, 95% CI = 0.70-1.01, P = 0.062). There were no significant differences in clinical pregnancy, pregnancy loss, or any of the measured obstetric and neonatal outcomes between groups. However, women in the ≤ 30 days' subgroup were associated with a significant reduction in positive HCG (adjusted OR = 0.52, 95% CI = 0.33-0.84, P = 0.007), clinical pregnancy (adjusted OR = 0.60, 95% CI = 0.38-0.95, P = 0.029), and live birth rates (adjusted OR = 0.51, 95% CI = 0.31-0.83, P = 0.006) compared to those in the non-infected group, while no such association was observed with the other subgroups. CONCLUSIONS: In those undergoing FET, overall, prior SARS-CoV-2 infection does not adversely affect live birth and perinatal outcomes. However, considering the decreased likelihood of live birth among women with shorter intervals, delaying the subsequent FET for at least 30 days after infection could be beneficial.