COVID‐19 Infection as a Risk Factor for Preterm Labour: A Retrospective Cohort Study

ABSTRACT Objective To evaluate COVID‐19 infection during pregnancy as a risk factor for preterm labour. Methods Following institutional review board approval, a single‐institution retrospective chart review was conducted on 2760 patients, with 2397 meeting inclusion criteria. Pregnant women delivering after 20 weeks between 1 March 2020 and 31 December 2021 were included. Exclusion criteria included no documented COVID test, multifetal gestations, deliveries under 20 weeks or delivery at another institution. The primary outcome was preterm labour incidence among those with COVID‐19, assessed by gestational age at delivery. Statistical analyses included chi‐squared tests, Fisher's exact tests and two‐sample t ‐tests with significance set at p < 0.05. The study had 80% power. Results Of 2397 patients, 200 were COVID‐positive, and 2197 were COVID‐negative. Preterm labour occurred in 12.0% of COVID‐positive cases versus 10.3% of COVID‐negative cases ( p = 0.523, RR 1.17, 95% CI 0.79–1.73), with no significant differences in demographics or other clinical factors between groups. After adjusting for patient demographics (age, race and parity) and patient variables (gestational age at delivery, BMI, tobacco use, recreational drug use, pregestational or gestational diabetes, chronic hypertension, current diagnosis of hypertensive disorders including gestational hypertension, pre‐eclampsia with or without severe features, STIs, PPROM, history of preterm delivery and history of pre‐eclampsia in prior pregnancies), COVID‐19 was not associated with increased risk of preterm labour ( p = 0.532). Conclusion COVID‐19 infection in pregnancy was not associated with significantly increased risk of preterm labour. These results help guide physician counselling and address patient concerns regarding COVID‐19 risks during pregnancy.