Impact of SARS-CoV-2 infection on risk of prematurity, birthweight and obstetric complications: A multivariate analysis from a nationwide, population-based retrospective cohort study

Objective: To determine the impact of maternal coronavirus disease 2019 (COVID-19) on prematurity, birthweight and obstetric complications.

Design: Nationwide, population-based retrospective cohort study.

Setting: National Programme de Médicalisation des Systèmes d'Information database in France.

Population: All single births from March to December 2020: 510 387 deliveries, including 2927 (0.6%) with confirmed COVID-19 in the mother and/or the newborn.

Methods: The group with COVID-19 was compared with the group without COVID-19 using the chi-square test or Fisher's exact test, and the Student's t test or Mann-Whitney U test. Logistic regressions were used to study the effect of COVID-19 on the risk of prematurity or macrosomia (birthweight ≥4500 g).

Main outcome measures: Prematurity less than 37, less than 28, 28-31, or 32-36 weeks of gestation; birthweight; obstetric complications.

Results: In singleton pregnancies, COVID-19 was associated with obstetric complications such as hypertension (2.8% versus 2.0%, p < 0.01), pre-eclampsia (3.6% versus 2.0%, p < 0.01), diabetes (18.8% versus 14.4%, p < 0.01) and caesarean delivery (26.8% versus 19.7%, p < 0.01). Among pregnant women with COVID-19, there was more prematurity between 28 and 31 weeks of gestation (1.3% versus 0.6%, p < 0.01) and between 32 and 36 weeks of gestation (7.7% versus 4.3%, p < 0.01), and more macrosomia (1.0% versus 0.7%, p = 0.04), but there was no difference in small-for-gestational-age newborns (6.3% versus 8.7%, p = 0.15). Logistic regression analysis for prematurity showed an adjusted odds ratio (aOR) of 1.77 (95% CI 1.55-2.01) for COVID-19. For macrosomia, COVID-19 resulted in non-significant aOR of 1.38 (95% CI 0.95-2.00).

Conclusions: COVID-19 is a risk factor for prematurity, even after adjustment for other risk factors.

Tweetable abstract: The risk of prematurity is twice as high in women with COVID-19 after adjustment for factors usually associated with prematurity.