New studies provide more evidence that pregnant women may get severe Covid-19 symptoms and have an increased risk of pregnancy loss.

The troubling findings are consistent with some earlier reports that pregnant women may be at increased risk for severe illness when they become infected with the new coronavirus.

But some experts warned that the findings, drawn from relatively small numbers of patients, including many hospitalized because of Covid-19, may not be representative of all pregnant women who are infected.

The studies found that many hospitalized pregnant women who were infected with the virus did not have any symptoms.

Among those who did have symptoms, however, between 16 percent and 30 percent required intensive care, and 6 percent to 8.5 percent required ventilators to help with breathing.

and senior author of one of the studies, said an important finding was that so many pregnant women who had no symptoms of Covid-19 were infected with the virus.

“If testing policies just focus on symptomatic women, we may miss the asymptomatic ones.”.

One study looked at 598 pregnant women with Covid-19 hospitalized in 13 states from March 1 through Aug 22.

Among the 272 pregnant women who had symptoms, 16 percent required intensive care, and 8.5 percent required ventilators to help with breathing.

Both symptomatic and asymptomatic women had premature births and pregnancy losses, though preterm births affected about 25 percent of symptomatic women, compared with only 8 percent of the asymptomatic women.

Ten women, or 2.2 percent, some symptomatic and some not, had miscarriages or stillbirths.

report looked at 105 hospitalized pregnant women from March 1 to May 30 who were infected with the virus, most of whom had been admitted for a pregnancy-related reason or because they were in labor.

About 30 percent of those hospitalized because of Covid required intensive care and 14 percent required a ventilator