Association between SARS-CoV-2 Infection and Adverse Perinatal Outcomes in a Large Health Maintenance Organization

Objective This study aimed to examine whether severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection during pregnancy is associated with increased odds of perinatal complications and viral transmission to the infant. Study Design A retrospective cohort study of women who delivered at Kaiser Permanente Southern California hospitals (April 6, 2020-February 28, 2021) was performed using data extracted from electronic health records (EHRs). During this time polymerize chain reaction (PCR)-based tests for SARS-CoV-2 was universally offered to all pregnant women at labor and delivery admission, as well as earlier in the pregnancy, if they were displaying symptoms consistent with SARS-CoV-2 infection or a possible exposure to the virus. Adjusted odds ratio (aOR) was used to estimate the strength of associations between positive test results and adverse perinatal outcomes. Results Of 35,123 women with a singleton pregnancy, 2,203 (6%) tested positive for SARS-CoV-2 infection with 596 (27%) testing positive during the first or second trimester and 1,607 (73%) during the third trimester. Women testing positive were younger than those who tested negative (29.7 [5.4] vs. 31.1 [5.3] years; mean [standard deviation (SD)]; p < .001). The SARS-CoV-2 infection tended to increase the odds of an abnormal fetal heart rate pattern (aOR: 1.10; 95% confidence interval [CI]: 1.00, 1.21; p = 0.058), spontaneous preterm birth (aOR: 1.28; 95% CI: 1.03, 1.58; p = 0.024), congenital anomalies (aOR: 1.69; 95% CI: 1.15, 2.50; p = 0.008), and maternal intensive care unit admission at delivery (aOR: 7.44; 95% CI: 4.06, 13.62; p < 0.001) but not preeclampsia/eclampsia (aOR: 1.14; 95% CI: 0.98, 1.33; p = 0.080). Eighteen (0.8%) neonates of mothers who tested positive also had a positive SARS-CoV-2 test after 24 hours of birth, but all were asymptomatic during the neonatal period. Conclusion These findings suggest that prenatal SARS-CoV-2 infection increases the odds of some adverse perinatal outcomes. The likelihood of vertical transmission from the mother to the fetus was low (0.3%), suggesting that pregnancy complications resulting from SARS-CoV-2 infection pose more risk to the baby than transplacental viral transmission.