# Influence of COVID-19 infection on early pregnancy outcomes in different periods around frozen embryo transfer

## TL;DR

This study found that mild or asymptomatic COVID-19 infections around the time of frozen embryo transfer do not significantly affect early pregnancy outcomes.

## Contribution

The study provides new evidence on the safety of frozen embryo transfers during mild or asymptomatic COVID-19 infections.

## Key findings

- Ongoing pregnancy rates were not significantly different across groups with infections at various times around FET.
- Early spontaneous abortion rates showed no significant differences between infection timing groups.
- Multivariable analysis found no significant correlation between infection and ongoing pregnancy.

## Abstract

The study aimed to investigate the potential influence of COVID-19 infection on embryo implantation and early development in women undergoing frozen embryo transfer (FET), with a specific focus on infections occurring at different periods around FET.

A retrospective analysis was performed on women who had undergone FET during a period marked by a significant surge in COVID-19 infection in Shanghai. All enrolled women experienced their first documented COVID-19 infection around the time of FET, ensuring that infections did not occur prior to oocyte retrieval. Participants were categorized into six groups based on the timing of infection: uninfected, ≥ 60 days, < 60 days before FET, 0–14 days, 15–28 days, and 29–70 days after FET. Clinical outcomes were compared across these groups.

The infection rate among the total of 709 cases was 78.28%. Infected individuals exhibited either asymptomatic or mild symptoms. The ongoing pregnancy rates for the first four groups were 40.7%, 44.4%, 40.5%, and 34.2% (P = 0.709) respectively, biochemical pregnancy rates (59.1% vs. 61.1% vs. 67.6% vs. 55.7%, P = 0.471) and clinical pregnancy rates (49.6% vs. 55.6% vs. 55.4% vs. 48.1%, P = 0.749), all showed no significant differences. Early spontaneous abortion rates across all six groups were 18.3%, 20.0%, 25.0%, 28.9%, 5.4%, and 19.0% respectively, with no significant differences (P = 0.113). Multivariable logistic analysis revealed no significant correlation between the infection and ongoing pregnancy.

Asymptomatic or mild COVID-19 infections occurring around FET do not appear to have a significant adverse impact on early pregnancy outcomes.