The Impact of Past COVID-19 Infection on Pregnancy Rates in Frozen Embryo Transfer Cycles

Michal Youngster 1,2 Sarit Avraham 1,2 Odelia Yaakov 1,2 Moran Moran Landau Rabbi 1,2 Itai Gat 1,2 Gil Yerushalmi 1,2 Micha Baum 2,3,4 Ettie Maman 2,3,4 Alon Kedem 1,2,3 Ariel Hourvitz 1,2
1IVF Unit, Department of Obstetrics and Gynecology, Shamir Medical Center, Israel
2Sackler Faculty of Medicine, Tel-Aviv University, Israel
3IVF Unit, Herzliya Medical Centre, Israel
4IVF Unit, Department of Obstetrics and Gynecology, Sheba Medical Centre, Israel

Introduction:
SARS-CoV-2 enters target host cells via the cellular receptor angiotensin-converting enzyme 2 (ACE2) and the cellular protease transmembrane protease serine-2 (TMPRSS2), which are expressed in the endometrium, possibly affecting implantation.

Study Aim:
To study the effect of COVID-19 infection on pregnancy rates in frozen embryo transfer (FET) cycles.

Methods:
A retrospective cohort study including women under the age of 42 with documented COVID-19 up to one year prior to treatment, undergoing FET cycles in the first half of 2021, with transfer of embryos generated prior to the infection. Controls were SARS-CoV-2 non-diagnosed, non-vaccinated women matched by age, number and day of embryo transfer.

Results:
Forty-one Recovered women and 41 controls were included. Pregnancy rates were 29 % and 49% respectively (p=0.070). Stratification by time from SARS-CoV-2 infection to transfer into ≤60 and >60 days revealed a difference in pregnancy rates, with women in the COVID group having lower pregnancy rates if infected in proximity to the transfer (21% vs. 55%; p=0.006). In a logistic regression model, infection was a significant variable (p=0.05, OR 0.325, 95% CI 0.106-0.998). Logistic regression applied on the subgroup of women infected in proximity to the transfer, further strengthened the univariate results, with COVID-19 remaining a significant parameter (p=0.005, OR 0.072, 95% CI 0.012-0.450).

Conclusions:
In FET cycles of patients with past SARS-CoV-2 infection, in which oocytes were retrieved prior to infection, decreased pregnancy rates were observed, specifically in patients who recovered less than 60 days prior to embryo transfer.