Pregnant women with COVID-19 appear to be at greater risk for common pregnancy complications — in addition to health risks from the virus — than pregnant women without COVID-19, suggests a study funded by the National Institutes of Health.

The study, which included nearly 2,400 pregnant women infected with SARS-CoV-2, found that those with moderate to severe infection were more likely to have a cesarean delivery, to deliver preterm, to die around the time of birth, or to experience serious illness from hypertensive disorders of pregnancy, postpartum hemorrhage, or from infection other than SARS-CoV-2. They were also more likely to lose the pregnancy or to have an infant die during the newborn period. Mild or asymptomatic infection was not associated with increased pregnancy risks.

“The findings underscore the need for women of child-bearing age and pregnant individuals to be vaccinated and to take other precautions against becoming infected with SARS-CoV-2,” said Diana Bianchi, MD, director of NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), which funded the study. “This is the best way to protect pregnant women and their babies.”

The study was conducted by Torri D. Metz, MD, of the University of Utah, Salt Lake City, and colleagues in the NICHD Maternal-Fetal Medicine Units Network. It appears in the Journal of the American Medical Association. Additional funding was provided by NIH’s National Center for Advancing Translational Sciences.

The study included more than 13,000 pregnant individuals from 17 U.S. hospitals, approximately 2,400 of whom were infected with SARS-CoV-2. Participants delivered between March 1 and December 31 2020, before SARS-CoV-2 vaccination was available. The researchers compared outcomes among those with COVID-19 to those of uninfected patients, and tabulated the study results as a primary outcome — whether the patient had died from any cause or had a serious illness or condition related to common obstetric complications. They also evaluated the results in terms of several secondary outcomes, including cesarean delivery, preterm birth, and fetal and newborn death.

Compared to uninfected patients, those with moderate to severe COVID-19 were more likely to experience the primary outcome, (26.1 vs 9.2%). They were also more likely to deliver by cesarean (45.4 vs 32.4%) or preterm (26.9 vs 14.1%) or to have a fetal or newborn death (3.5 vs 1.8%). Mild or asymptomatic COVID-19 was not associated with any of adverse outcomes.

This news release was originally published by the National Institutes of Health on February 7, 2022.