There's even more evidence premature birth rates are dropping during the pandemic

• A study indicates that the rate of premature birth is down up to 23%.
• The cause of premature births — and how to stop them — is still a mystery in many cases.
• Doctors say that the pandemic could yield clues about what causes premature births, but that expecting mothers should still be aware of their risk for early labor.

The pandemic often seems like one bad-news item after another. But for parents, there might be a small silver lining — new research is strengthening the evidence that premature birth rates may be dropping.

A study from the Netherlands, published October 13 in The Lancet, compared gestational age of babies born during the lockdown, beginning in March, to data from previous years. Looking at different windows of time, the researchers found that premature birth rates were down between 15 to 23%, neonatologist and lead study author Jasper Been told the New York Times.

"We could see that this impact was real," he added.

The study builds on two preliminary reports from Denmark and Ireland that were released during the summer. In both of those reports — which were compiled and published independent of each other, but at similar times — doctors found that premature birth rates had dropped drastically.

The importance of understanding premature birth

Diana Garretto, MD, an OB-GYN and maternal fetal medicine specialist at Stony Brook Medicine in New York, told Insider that there are many factors impacting premature births. With such a complex issue, the research is more nuanced than headlines might indicate.

"It's complicated," she said.

In the United States, just under 10% of babies are born premature, defined as delivery before 37 weeks gestation. Being born premature puts babies at risk for a host of lifelong health issues, ranging from breathing trouble to developmental delays. Premature infants, especially those born very early, are also at increased risk for death.

Garretto divides premature births into two groups. Iatrogenic premature births are caused by an underlying health condition that means the mother must deliver early. Inductions made by doctors for conditions like preeclampsia or restricted fetal growth fall into this category.

Spontaneous premature labor happens without any clear cause, and doctors can do little to control it, she said.

"That's one of the areas that we're not that great at," Garretto said. "Our success rate [at stopping early spontaneous labor] is pretty low."

While doctors understand some risk factors for premature birth, including having diabetes and carrying multiples, "there are a lot of things that we don't understand," Garretto said.

A glimpse into the premature birth mystery

If research continues to support the idea that premature births are down during the pandemic, it could give scientists clues about the factors that influence premature births, especially spontaneous ones.

"We haven't been able to reduce the preterm birthrate come hell or high water," Jennifer Culhane, a senior research scientist in obstetrics and gynecology at Yale School of Medicine, told The New York Times.

Data from the pandemic — a circumstance that scientists could never devise for a controlled study — could help answer some of the questions about premature birth. Garretto says it's possible that being at home helped shield pregnant women from some work-related stress. Certain viruses have also been linked to premature births, she said, so it's possible that fewer women were exposed while social distancing.

On the other hand, many people have experienced more stress during the pandemic, so it's hard to say whether the lockdowns would have been an overall positive or negative for pregnant women, she said.

Scientists don't entirely understand how premature births have been impacted by the pandemic

There's not yet any data about preemie rates in the United States this year. However, Culhane said that she's heard anecdotal reports of fewer preemies, so she's working on a study that will examine preemie rates in the U.S.

Garretto, however, hasn't seen a change.

"I can't see we've seen any less than our usual," she said.

The emerging research is compelling, but it will be a while before scientists truly understand premature births, or how they were impacted by the pandemic, Garretto said.

There could be a less positive explanation as well. The researchers in The Netherlands pointed out that stillborn babies were not included in their data set. Theoretically, the decrease in premature births could have been because more infants were dying. There's not any data to support that yet, but it's worth investigating, they wrote.

Garretto says that research will need to account for the fact that people with high-risk pregnancies, who are more likely to experience preterm labor, might be opting not to have babies during the pandemic. While that wouldn't explain a decrease in preemie births during the early months, it could affect rates next year and beyond.

It's important that people recognize premature birth is still a real health risk, and learn to recognize the warning signs of premature labor. Pregnant women should remain alert during the pandemic, Garretto said.

"I don't think they should take away that the risk factors no longer exist," she said.

• Read more:
• I'm 38 weeks pregnant and I have to give birth alone. If my husband could get tested for the coronavirus, it wouldn't have to be that way.
• Suicide is a leading cause of death in new moms. A simple text message could help.
• Some parents say they're not homeschooling during the coronavirus pandemic because it's too stressful