SARS-CoV-2 infection in IVF-conceived early pregnancy and the risk of miscarriage: a matched retrospective cohort study.

Study question: Is SARS-CoV-2 infection in IVF-conceived early pregnancy associated with a higher risk of miscarriage?

Summary answer: Infection with SARS-CoV-2 during early pregnancy in women conceiving by IVF may not be associated with an increased rate of miscarriage.

What is known already: In naturally conceived pregnancies, most findings have shown that SARS-CoV-2 infection does not increase the risk of miscarriage, while some studies have shown that SARS-CoV-2 infection is associated with a higher risk of miscarriage.

Study design size duration: A matched retrospective cohort study was conducted in a tertiary hospital-based reproductive medicine center. The infection group included women who contracted coronavirus disease 2019 (COVID-19) before 20 weeks gestation from 6 December 2022 to 10 January 2023. Each infected woman was matched with three historical control subjects from 1 January 2018 to 31 May 2022.

Participants/materials setting methods: The infection group was matched with historical control subjects based on female age (±1 year), number of gestational sacs, number of previous miscarriages, BMI (±2 kg/cm²), main causes of infertility, gestational week, and fresh versus frozen embryo transfer.

Main results and the role of chance: A total of 150 pregnant women infected with COVID-19 before 20 weeks of gestation were included in the infection group, which was matched at a 3:1 ratio with 450 historically pregnant controls. There were no significant differences in age, BMI, and endometrial thickness between the two groups. The overall incidence of miscarriage was not significantly different between the infection group and the control group (4.7% versus 5.8%, P = 0.68). When the infection group was stratified into three subgroups based on the gestational age at the onset of infection (0-7 + 6, 8-11 + 6, and 12-19 + 6 weeks), no significant differences were observed in the incidence of miscarriage between the infection group and the matched control group in any of the subgroups (9.8% versus 13.8%, P = 0.60; 5.4% versus 4.5%, P = 1.00; and 1.4% versus 1.9%, P = 1.00, respectively).

Limitations reasons for caution: The major limitation of this study is the relatively small sample size; therefore, caution is suggested when drawing any definitive conclusions. Nonetheless, our study is the largest sample study of the influence of COVID-19 infection on the miscarriage rate in early pregnancy after IVF.

Wider implications of the findings: Our findings may provide important insights for reproductive physicians and obstetricians during preconception and early pregnancy counseling.

Study funding/competing interests: This study was supported by the Natural Science Foundation of Guangdong Province (No. 2023A1515010250). The authors report no conflicts of interest.

Trial registration number: N/A.