COVID-19 Infection During Pregnancy and Associated Perinatal Health Outcomes: A National Cohort Study of US Pregnancies

Background: Emerging evidence suggests that COVID-19 infection is more severe in pregnant individuals and may be associated with increased risk of adverse perinatal health outcomes. However, few large-scale, community-based comparative epidemiological studies have evaluated pregnancy outcomes following COVID-19 infection.Methods: We conducted a national cohort study using de-identified administrative claims and electronic health record data from the OptumLabs® Data Warehouse. Every pregnancy with a last menstrual period before 30 April 2020 and date of pregnancy end after 11 March 2020 was included. We identified maternal infections using ICD-10-CM diagnostic code of U07.1 or a positive laboratory testing record for SARS-CoV-2. We compared the risk of adverse pregnancy outcomes using Cox proportional hazard models treating COVID-19 infection as a time-varying exposure, which were adjusted for baseline covariates.Findings: Of the 78,283 pregnancies identified, 2,655 (3·4%) had a documented COVID-19 infection. Infection was more prevalent among Black and Hispanic pregnant individuals and those with pre-existing medical conditions; 3·4% of COVID-19 cases required admission to intensive care, invasive mechanical ventilation or ECMO treatment. COVID-19 during pregnancy was associated with higher risk of medical termination (adjusted hazard ratio [aHR] 2·60; 95% CI 1·17, 5·78), cesarean section (aHR 1·99; 95% CI 1·71, 2·31), clinician-initiated preterm birth (2·88; 95% CI 1·93, 4·30), spontaneous preterm birth (aHR 1·79; 95% CI 1·37, 2·34), and fetal growth restriction (aHR 2·04; 95% CI 1·72, 2·43). Similar associations were observed by trimester of COVID-19 infection.Interpretation: Data from this US pregnancy cohort show increased risk of adverse pregnancy outcomes associated with prenatal COVID-19 infection during any trimester of pregnancy. Prevention of COVID-19 through vaccination, social distancing and other measures could prevent COVID-19-associated adverse pregnancy outcomes. Funding Information: Access to study data was financially supported by OptumLabs® and University of California Los Angeles. The WHO Collaborating Centre for Reference and Research on Influenza is supported by the Australian Government Department of Health.Declaration of Interests: We declare no competing interests.Ethics Approval Statement: Because this study involved analysis of pre-existing, de-identified data, it was considered exempt from Institutional Review Board approval.