Women infected with the virus may also be at greater risk of losing the pregnancy or stillbirth.
Many pregnant women who were infected with the virus were hospitalized without any symptoms, according to the studies. Among those with symptoms, between 16% and 30% required intensive care and between 6% and 8.5% were put on ventilators. Of the 703 cases documented in the two reports, three women died.
Both studies found that pregnant woman with the virus had a higher rate of premature deliveries and some had still births, according to the Times.
As the immune system is suppressed during pregnancy, mothers become more vulnerable to infection. The lungs may also be affected by the expanding uterus and the cardiovascular system works harder, which may increase the women's vulnerability. The virus's effects on the placenta are still largely unknown.
"We now have data from three separate CDC surveillance systems all suggesting that pregnant women may be at increased risk for severe disease from COVID-19," said Dr. Denise Jamieson, a member of the COVID-19 task force at the American College of Obstetricians and Gynecologists, according to the Times.
"The take home message is that pregnant women can get seriously ill with this,” said Dr. Peter Bernstein, director of the division of maternal fetal medicine at Montefiore Medical Center in the Bronx, according to the Times. “We don’t know for sure that they will get sicker than they would have if they weren’t pregnant, but certainly there are women out there who are getting very sick and even dying.”
The data came from two CDC studies conducted in the past year.
One study included 598 pregnant women with COVID-19 who were hospitalized in 13 states between March 1 and August 22. One in five had a chronic health problem and over half of the women were asymptomatic when they were admitted to the hospital.
Of the 272 women who had symptoms, 16% needed intensive care and 8.5% needed ventilators. Two women died, according to the Times.
Some 458 of the 598 women completed the pregnancies while hospitalized and 448 had a live birth. Premature births affected 25% of symptomatic women compared to 8% of asymptomatic women.
The second study followed 105 women between March 1 and May 30. About 30% of those hospitalized because of COVID-19 required intensive care and 14% needed a ventilator.
While more research is still required, experts urge pregnant woman to be extra careful about coronavirus guidelines, including masks and social distancing, to avoid infection.