The incidence, characteristics and outcomes of pregnant women hospitalized with symptomatic and asymptomatic SARS-CoV-2 infection in the UK from March to September 2020: A national cohort study using the UK Obstetric Surveillance System (UKOSS)

PLoS One. 2021 May 5;16(5):e0251123. doi: 10.1371/journal.pone.0251123. eCollection 2021.


Background: There is a lack of population level data on risk factors, incidence and impact of SARS-CoV-2 infection in pregnant women and their babies. The primary aim of this study was to describe the incidence, characteristics and outcomes of hospitalized pregnant women with symptomatic and asymptomatic SARS-CoV-2 in the UK compared to pregnant women without SARS-CoV-2.

Methods and findings: We conducted a national, prospective cohort study of all hospitalized pregnant women with confirmed SARS-CoV-2 from 01/03/2020 to 31/08/2020 using the UK Obstetric Surveillance System. Incidence rates were estimated using national maternity data. Overall, 1148 hospitalized women had confirmed SARS-CoV-2 in pregnancy, 63% of which were symptomatic. The estimated incidence of hospitalization with symptomatic SARS-CoV-2 was 2.0 per 1000 maternities (95% CI 1.9-2.2) and for asymptomatic SARS-CoV-2 was 1.2 per 1000 maternities (95% CI 1.1-1.4). Compared to pregnant women without SARS-CoV-2, women hospitalized with symptomatic SARS-CoV-2 were more likely to be overweight or obese (adjusted OR 1.86, (95% CI 1.39-2.48) and aOR 2.07 (1.53-2.29)), to be of Black, Asian or Other minority ethnic group (aOR 6.24, (3.93-9.90), aOR 4.36, (3.19-5.95) and aOR 12.95, (4.93-34.01)), and to have a relevant medical comorbidity (aOR 1.83 (1.32-2.54)). Hospitalized pregnant women with symptomatic SARS-CoV-2 were more likely to be admitted to intensive care (aOR 57.67, (7.80-426.70)) but the absolute risk of poor outcomes was low. Cesarean births and neonatal unit admission were increased regardless of symptom status (symptomatic aOR 2.60, (1.97-3.42) and aOR 3.08, (1.99-4.77); asymptomatic aOR 2.02, (1.52-2.70) and aOR 1.84, (1.12-3.03)). The risks of stillbirth or neonatal death were not significantly increased, regardless of symptom status.

Conclusions: We have identified factors that increase the risk of symptomatic and asymptomatic SARS-CoV-2 in pregnancy. Clinicians can be reassured that the majority of women do not experience severe complications of SARS-CoV-2 in pregnancy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • COVID-19 / complications
  • COVID-19 / diagnosis
  • COVID-19 / epidemiology*
  • COVID-19 / virology
  • Carrier State / diagnosis
  • Carrier State / epidemiology*
  • Carrier State / virology
  • Cesarean Section
  • Cohort Studies
  • Databases, Factual
  • Female
  • Humans
  • Incidence
  • Intensive Care Units
  • Minority Groups / statistics & numerical data
  • Obesity / complications
  • Odds Ratio
  • Pregnancy
  • Pregnancy Outcome*
  • Pregnant Women
  • Prospective Studies
  • SARS-CoV-2 / isolation & purification
  • United Kingdom / epidemiology
  • Young Adult

Grant support

The study was funded by the National Institute for Health Research HS&DR Programme (project number 11/46/12; MK is an NIHR Senior Investigator who received this award. MK, MQ, PB, PO’B, JJK received grants from the NIHR in relation to the submitted work. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. The funder played no role in study design; data collection and analysis, decision to publish or preparation of the manuscript. The corresponding author (MK) had full access to all the data in the study and had final responsibility for the decision to submit for publication.