Incidence, Risk Factors and Outcomes of SARS-CoV-2 Infection in Pregnant Women in France, the COROPREG study
Since the beginning of the COVID-19 pandemic, pregnant women have been considered a particularly at-risk group, largely due to early publications on the subject. However, these studies often only included hospitalized women, leading to a selection bias in the studied population. Moreover, the severity of the infection was often assessed solely based on management criteria, which varied across hospitals, countries, and over time. Therefore, robust, large-scale population-based data were needed to accurately document the impact of COVID-19 during pregnancy.
The Coropreg study was conducted between March 2020 and April 2021 in 281 maternity units across six French regions, covering 60% of the country’s births, and included 6,222 women infected with SARS-CoV-2 during pregnancy or shortly after delivery. The study aimed to 1) Estimate the incidence of maternal COVID-19 infection in France; 2) Identify risk factors for developing severe forms of the disease; 3) Describe the consequences of the infection on childbirth, as well as on maternal and neonatal health.
It involved the development of a composite definition of severity, including clinical, biological, and management criteria of organ-dysfunction.
Main findings:
- Approximately 6 in 1,000 pregnant women experienced a severe form of COVID-19 during their pregnancy over the study period.
- Severe forms affected an average of 5.6% of infected women, with peaks at 8.6% during the first wave and 9.3% during the third wave (Alpha variant).
- The risk of developing a severe infection was higher among women under 20 or over 35 years old, those from North or Sub-Saharan Africa, those living in households with more than four people, women who were overweight or obese, those with pre-existing diabetes or hypertension, and those infected after the 22nd week of pregnancy.
- Neonatal adverse outcomes appeared to be confined to severe maternal infections and, to some extent, attributable to induced prematurity.
Conclusions:
- Severe forms of maternal COVID-19 were less frequent than initially reported in early studies.
- They predominantly affected women who were socially and/or medically vulnerable.
- The infant consequences were most serious when the mother was severely affected, particularly for infants born prematurely.
- A continuous perinatal surveillance system would be crucial for better management of future pandemics.
Read the article: Incidence, Risk Factors and Outcomes of SARS-CoV-2 Infection in Pregnant Women: The COROPREG Population-Based Study. Paediatr Perinat Epidemiol. 2025 May 21.
By Catherine Deneux, Caroline Diguisto, Aurélien Seco, Pierre-Yves Ancel
