NEW HAVEN — Fewer than 3 percent of women admitted to three Yale New Haven Health hospitals for labor and delivery who did not have symptoms of COVID-19 tested positive for the disease, according to a new study.

The research, published as a letter Tuesday in JAMA, involved 770 women who had not been tested for the disease. They were admitted to Yale New Haven, Bridgeport and Greenwich hospitals in April.

Just 30 of the patients tested positive, and 22 of those had shown no symptoms when admitted to the hospital.

The study’s authors said the results show that normal precautions of surgical masks, gloves and gowns are adequate when caring for mothers-to-be who do not have symptoms of COVID-19. Medical staff who care for patients with COVID symptoms must wear N95 respirator masks and other personal protective equipment not normally worn, according to a press release.

“Our report provides reassuring information on infection rates and appropriate hospital responses outside of highly endemic areas,” said Dr. Katherine H. Campbell, medical director at Yale New Haven Hospital’s labor and birth and maternal special care units, in the release.

“Not only have we provided insight into the nature of a positive test, we’ve highlighted how a comprehensive testing program can reduce the use of personal protective equipment among labor and delivery staff without increasing their risk of exposure,” she said. Campbell was a corresponding author of the study.

A similar study undertaken at two New York City hospitals, where the coronavirus has been more highly prevalent than in Connecticut, found that 13.5 percent of asymptomatic pregnant women tested positive for COVID.

The study did find the number of women without symptoms who tested positive increased tenfold during the study, but those who had symptoms decreased by half, the release said.

Dr. Christian Pettker, chief of obstetrics at Yale New Haven Hospital and an author of the study, said those findings were positive, because patients who have recovered from COVID-19 can test positive for up to six weeks afterward.

“Given our data, we think that a large number of the asymptomatic patients who test positive might not actually be actively infected or infectious,” he said in the release. “This requires more research but has very important implications for patients who test positive who then might have to be isolated and separated from their babies.

“From a patient standpoint, this actually might be even more newsworthy than the point that labor units are much safer than has been reported,” he said.

Connecticut Media Group