Perinatal outcomes after admission with COVID-19 in pregnancy: a UK national cohort

Abstract

Abstract BACKGROUND There are few population-based studies of sufficient size and follow-up duration to have reliably assessed perinatal outcomes for pregnant women admitted to hospital with SARS-CoV-2 infection. METHODS The United Kingdom Obstetric Surveillance System (UKOSS) includes all 194 consultant-led UK maternity units. From March 2020 to March 2022, pregnant women admitted with a positive SARS-CoV-2 PCR test within seven days before or during admission were included and categorised by dominant SARS-CoV-2 variant, severity of maternal COVID-19 and vaccination status. RESULTS In total, 16,351 infants were born to 16,627 women; women with symptomatic COVID-19 contributed 7,116 (43.3%) births, 111 of which were stillborn. Infection during the delta variant period was associated with increased risk of stillbirth irrespective of infection severity compared to mild wild-type infection (mild wildtype 0.8% vs. mild delta 3%, adjusted risk ratio [aRR] 3.57, 95% confidence interval [CI] 1.66 to 7.67; vs. moderate to severe delta, 1.9%, aRR2.41; 95%CI 1.03 to 5.60). All variants were associated with increased risk of preterm birth in women with moderate to severe infection compared to women with mild infection in the wildtype period. After introduction of vaccination during pregnancy, 91.2% (83/91) of stillbirths and 92.1% (422/459) of preterm births < 34 weeks’ gestation were in symptomatic women with no documented vaccination or with unknown vaccine status. CONCLUSION COVID-19 variant, severity, and no or unknown maternal vaccinations were key risk factors for adverse perinatal outcomes. There is strong evidence for continued recommendation of SARS-CoV-2 vaccination during pregnancy to protect women and their babies.