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There May Be a Link Between COVID-19 and Preterm Birth, CDC Says

3 minute read

Contracting COVID-19 during pregnancy may put expectant mothers at a higher risk of delivering early, according to new data from the U.S. Centers for Disease Control and Prevention (CDC).

The CDC’s new report is based on data from almost 4,500 people who were diagnosed with COVID-19 during pregnancy and provided public health departments with information about their pregnancy outcomes. Roughly 3,900 mothers gave information about their baby’s gestational age. Within that group, nearly 13% of babies (about 500) were born preterm—slightly but significantly higher than the 2019 national rate of about 10%.

Preterm birth—a birth that occurs before the 37th week of pregnancy—has been on the rise around the world in recent years, though researchers aren’t entirely sure why. Preterm birth is the leading cause of death for children under five years old, according to the World Health Organization. Babies born early can experience both short- and long-term health problems, which tend to be more serious the earlier a baby is born.

Understanding a possible connection between COVID-19 and preterm birth could help inform obstetric care for the rest of the pandemic. Many of the characteristics that put people at increased risk for severe COVID-19 infection, including preexisting health conditions, also increase the risk of preterm birth. Black women also experience higher-than-average rates of both preterm birth and COVID-19 infection. The CDC’s dataset disproportionately included women of color, many of whom had prior health problems, so it’s possible the data reflects some of those preexisting disparities.

The CDC’s report didn’t specify why pregnant women may be at risk of delivering early, but prior studies suggest expectant mothers who get sick with coronavirus are more likely than the general population to have severe symptoms and require intensive care. There may be a link between the two findings.

The report also found that babies were fairly unlikely to contract COVID-19 in the womb. Test results were not available for most babies included in the study, but among the 610 with results available, only 2.6% tested positive within a week of birth. Women diagnosed with COVID-19 a week or less before giving birth appeared to be the most likely to pass the virus to their child, according to the agency.

Half of the babies that tested positive for COVID-19 were born early, but this high positivity rate may reflect better testing practices within intensive care units, the report says.

The CDC’s recommendations for pregnant women and their families are the same as for the general population: wear masks in public spaces, practice social distancing and wash hands frequently. Pregnant women should also stay up-to-date with vaccinations and prenatal appointments to ensure general health, the CDC says.

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Write to Jamie Ducharme at jamie.ducharme@time.com