COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

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Prognosis Vousden N, Bunch K, Morris E, et al. 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.

Discipline / Specialty Area Score
Family Medicine (FM)/General Practice (GP)
Infectious Disease
Comments from MORE raters

Family Medicine (FM)/General Practice (GP) rater

Covid-19 infection seems to follow the same pattern impacting those from minority groups, those with comorbidities and obesity and leads to a higher risk of pre term birth. Maternal deaths associated with Covid-19 were increased but rare.

Infectious Disease rater

Useful study even though the analytical plan/approach was a bit shaky. Apart from maternal age and race, other additional confounding factors that were used in the analysis are not clearly indicated. Tables show various patient characteristics but it's unclear which ones were controlled for as confounding factors.

Infectious Disease rater

This is an interesting and well conducted study. We need to be careful about the external validity, because the case mix of the cohort, as well as the particular characteristics of both pregnant woman and the health service in the UK, deserve attention.

Obstetrics rater

It is a prospective observational cohort study which looked into the incidence, characteristics and outcomes of pregnant women who were admitted with asymptomatic and symptomatic SARS- COV- 2 infection. As in the many other studies which looked into the above variables, the results were similar in terms of patients characteristics and outcomes. The authors in this study suggested that the high risk category of patients such as Black, Asian, pregnant women with high BMI should be considered for inclusion and prioritization when testing SARS-CoV-2 vaccine efficacy and safety.