Pregnant women are not only at an increased risk of developing severe cases of Covid-19, but—in some instances—they have a 70% higher risk of death when compared with nonpregnant women, according to new CDC research.

500,000 fewer births next year? What Covid-19 could mean for pregnancy.

Report details

CDC released the findings in two new Morbidity and Mortality Weekly Reports.

For the first report, researchers reviewed data on 1,300,938 women ages 15 to 44 who tested positive for the novel coronavirus during the period spanning Jan. 22 to Oct. 3. The pregnancy status was known for 461,825 of the women, and 409,462 of the women for whom pregnancy status was known experienced symptoms of Covid-19. According to the report, 23,434 of those symptomatic women were pregnant.

According to the researchers, 34 of the pregnant women who experienced symptoms of Covid-19 died, with a rate of 1.5 per 1,000 cases. In comparison, 447 of the 386,028 nonpregnant women who experienced symptoms of Covid-19 died, with a rate of 1.2 per 1,000 cases. According to the researchers, the difference represents a 70% increased risk of death among pregnant women with Covid-19 symptoms when compared with nonpregnant symptomatic women.

The researchers also found that pregnant women with Covid-19 symptoms were more likely to require invasive ventilation than nonpregnant symptomatic women. Among the pregnant women who experienced symptoms of Covid-19, 67—or 2.9 per 1,000 cases—required ventilation, compared with 412—or 1.1 per 1,000 cases—among the nonpregnant women with Covid-19 symptoms.

Pregnant women were also at an increased risk of requiring treatment with extracorporeal membrane oxygenation (ECMO), a heart-lung bypass machine, the researchers found. According to the researchers, 17 pregnant women with Covid-19 symptoms required ECMO, at a rate of 0.7 per 1,000 cases,  compared with 120 nonpregnant symptomatic women, at a rate of 0.3 per 1,000 cases.

The researchers also found that, among the pregnant symptomatic women, 245, or 10.5 per 1,000 cases, were admitted into an ICU, compared with 1,492, or 3.9 per 1,000 cases, among nonpregnant symptomatic women.

The researchers identified significant racial and ethnic disparities in the women's health outcomes. For instance, the researchers found that 26.5% of the pregnant symptomatic women who died were Black, despite Black women representing just 14% of that group of women.

According to the researchers, symptomatic pregnant women's increased risk of severe Covid-19 could be related to the physical changes that occur during pregnancy, "including increased heart rate and oxygen consumption, decreased lung capacity, a shift away from cell-mediated immunity, and increased risk for thromboembolic disease."

For the second report, researchers looked at a sample of 3,912 live births among women who tested positive for the novel coronavirus that occurred during the period spanning March 29 to Oct. 14. The researchers found that 12.9% of those delivers occurred preterm, which is higher than the national rate of 10.2% among the general U.S. population. According to the researchers, frequency of preterm birth did not have any associations with whether the pregnant women had experienced symptoms of Covid-19.

What do the findings mean?

Sascha Ellington, a health scientist with CDC and one of the authors of the first report, explained, "Previously [CDC] said [pregnant women] 'might be' at increased risk for severe illness" from Covid-19. However, CDC is "now saying pregnant women are at increased risk for severe illness," Ellington said.

Ellington emphasized that the overall risk among pregnant women with Covid-19 for both complications and death was low, "but what we do see is an increased risk associated with pregnancy."

Denise Jamieson, chair of gynecology and obstetrics at Emory University School of Medicine, said the reports emphasize how important it is for pregnant women to avoid exposure to the novel coronavirus.

"This is new information that adds to the growing body of evidence, and really underscores the importance of pregnant women protecting themselves from Covid," Jamieson said. "It's important that they wear a mask and avoid people who are not wearing a mask."

David Jaspan, chair of the obstetrics and gynecology department at Einstein Healthcare Network, said some people may think they'll be fine if they develop Covid-19 because they're young and healthy, "[b]ut the fact is at my practice, we've seen women who are pregnant on ventilators. It affects the mother, the delivery, and the baby."

Jaspan added, "We have no predictive ability how this will impact you, so the best advice we can offer is prevention. Wear a mask. Social distance. Stay away from people who may be infected" (Rabin, New York Times, 11/2; Owens, "Vitals," Axios, 11/3; Wan, Washington Post, 11/2).