COVID-19 increases the risk of stillbirth for pregnant women — 65% of whom still aren't vaccinated

• COVID-19 increases the risk of stillbirth among pregnant women, a new CDC report found.
• Around 1.3% of babies born to women with COVID-19 were stillborn from March 2020 to September 2021.

The data has been clear for some time: Pregnant women are at increased risk of developing severe COVID-19. They're also nearly twice as likely to die from COVID-19 as women the same age who aren't pregnant.

But until now, researchers were unable to confirm whether COVID-19 increased stillbirth risk — meaning the loss of a baby on or before the 20th week of pregnancy. A report from the Centers for Disease Control and Prevention, released Friday, adds clarity. Pregnancy loss is indeed a risk factor for pregnant women who contract COVID-19, the CDC found — particularly amid the Delta variant's takeover in the US.

CDC researchers examined the relative risk of stillbirth from March 2020 to September 2021 in the US, and found that around 1.3% of babies born to women with COVID-19 were stillborn, compared with 0.6% of babies born to women who weren't infected with COVID-19.

Stillbirths were more strongly associated with COVID-19 from July to September of this year, after the Delta variant became dominant. During that time, 2.7% of babies born to women with COVID-19 were stillborn, whereas the rate of stillborn deliveries among women without COVID-19 remained relatively unchanged.

Overall COVID-19 death rates were higher among pregnant women once Delta became dominant. A second CDC report released Friday identified 25 deaths for every 1,000 coronavirus infections during pregnancy in Mississippi from July to October of this year, compared with five deaths for every 1,000 coronavirus infections during pregnancy from March 2020 to June 2021.

The CDC suggests a possible explanation for those preterm and stillborn deliveries: COVID-19 may reduce blood flow to and increase inflammation in the placenta — conditions that make it difficult for a fetus to survive.

CDC researchers called for additional study into whether vaccines could help prevent stillbirths linked to COVID-19 infections.

Vaccines are a critical tool for reducing COVID-19-linked stillbirths

While the researchers weren't able to determine the vaccination rates among pregnant women who gave birth to stillborn babies, they suggested that most women with COVID-19 at delivery likely weren't vaccinated. That's because vaccines lower the risk of COVID-19, and vaccination rates are considerably low among pregnant women in the US.

As of November 13, around 65% of pregnant women weren't fully immunized prior to or during their pregnancy, according to CDC data.

Getting vaccinated before or during pregnancy "is critical to reduce the impact of COVID-19 on stillbirths," the CDC researchers wrote.

Previous studies have shown that pregnant women with COVID-19 are at increased risk for delivering preterm babies, born earlier than 37 weeks. A July study in The Lancet Regional Health, for example, found that a COVID-19 diagnosis increased the risk of preterm birth during pregnancy by 40%, and very preterm birth (before 32 weeks) by 60%.