Incidence, Risk Factors and Outcomes of SARS-CoV-2 Infection in Pregnant Women: The COROPREG Population-Based Study

Population-based data are needed to reliably assess the impact of SARS-CoV-2 infection during pregnancy.

To estimate the population-based incidence of SARS-CoV-2 infection and its severe forms in the obstetric population, identify risk factors of severe SARS-CoV-2 infection (severe COVID-19) and describe delivery, maternal and neonatal outcomes by disease severity, using a definition of severity based on organ dysfunction.

A prospective population-based study conducted over the three first pandemic waves between March 2020 and April 2021 in 281 maternity hospitals in six French regions included all women with SARS-CoV-2 infection during pregnancy or within 7 days post-partum, whether symptomatic or not, hospitalised or not. Severe COVID-19 forms were defined a priori using clinical, biological and management criteria of organ dysfunction. We calculated infection and severe infection rates and studied associations between sociodemographic, medical and pregnancy characteristics and severe COVID-19 by univariate and multivariate modified Poisson regression modelling.

From a population of 385,214 deliveries in the participating regions, 6015 women with SARS-CoV-2 infection were identified, including 337 severe cases. The rates of severe COVID-19 were 1.1, 0.9 and 3.6 per 1000 deliveries during the first, second and third pandemic waves, respectively, and the proportions of severe COVID-19 were 8.6%, 3.4% and 9.3%, respectively. On multivariate analysis, the risk of severe COVID-19 was associated with younger and older age, migrant status, living with > 4 people, overweight or obesity, chronic hypertension or diabetes and infection ≥ 22 weeks of gestation rather than earlier in pregnancy. Neonatal morbidity occurred mostly with severe maternal infection.

Using an organ-based definition of severity and population-based data, rates of severe COVID-19 appeared lower than in previous studies. A permanent perinatal surveillance system is needed to assess efficiently and rapidly the impact of future pandemics.