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Most pregnant women with coronavirus had no symptoms, study finds

The findings may offer a possible glimpse into the prevalence of people who have COVID-19 but show no signs of it in New York City.
/ Source: TODAY

When two New York City hospitals recently began screening every pregnant woman who was admitted to give birth for COVID-19, doctors made a startling discovery: About one in eight women tested positive, but the vast majority of them showed no symptoms.

“It’s only two weeks of data and we’ll certainly continue to collect and further publish on that data, but it really did show that 13.5% of women showing up feeling well to have a baby were coronavirus positive,” Dr. Dena Goffman, study co-author and chief of obstetrics at New York-Presbyterian Hospital and Columbia University Medical Center, told MSNBC’s Rachel Maddow.

But 88% who had the disease at admission had no symptoms of it when tested, offering a possible glimpse into the prevalence of asymptomatic COVID-19 cases in New York City. Researchers continue to investigate whether people who aren't coughing or sneezing can infect others.

The findings, published Monday in The New England Journal of Medicine, are based on 215 women who delivered babies at the New York–Presbyterian Allen Hospital and Columbia University Irving Medical Center between March 22 and April 4, 2020.

Four of the women had fever or other symptoms of COVID-19 on admission and all tested positive for the virus. Another 29 women tested positive even though they felt well. Thus, 29 of the 33 patients who were infected with the virus were asymptomatic.

Of those 29 asymptomatic women, three went on to develop a fever before being discharged, though this was attributed to COVID-19 in only one case. (Endomyometritis, a complication of pregnancy, was presumed to be the cause in the other two cases.)

The universal screening at the two hospitals was implemented last month after two women were admitted for routine labor and delivery, and were later found to have the new coronavirus. Both felt well at first, but soon developed symptoms and became sick. They’d been hospitalized for a while before being diagnosed with COVID-19, potentially exposing “a huge portion or our workforce” to the virus, Goffman said.

“Once we made the diagnosis, it sort of clicked that there were women who may be asymptomatic and that we may want to think differently about it,” she noted.

Universal testing can help hospitals determine which patients to isolate, how bed assignments should be made, when personal protective equipment needs to be used, and how women and their newborns should be monitored.

“Having this information has numerous benefits for us and for the patient population,” Goffman said.

Pregnant women who have the coronavirus can possibly pass the infection onto their babies, though it's unclear whether the transmission occurs in the womb, from the birth canal or from microtears in the amniotic sac, a small study of 33 women in China found.

A newborn is susceptible to person-to-person spread after birth, the Centers for Disease Control and Prevention noted. Women who are sick and choose to breastfeed should wear a facemask and wash their hands before each feeding.

Data so far suggests COVID-19 has been mild for babies.