Nearly one in seven pregnant women in New York have tested positive for the coronavirus, but most of them exhibited minimal to no symptoms, a limited study revealed.

NewYork-Presbyterian and Columbia University Medical Centre swabbed 215 expectant mothers when they were admitted into the hospital to give birth between 22 March to 4 April.

Of those 215 women, 33 tested positive for the coronavirus and 29 of them showed no telling symptoms for the virus, such as fever or persistent cough, which made them "silent carriers" of Covid-19.

Three of these women that were asymptomatic later developed a fever while in the hospital, according to the study.

The other four women who tested positive for the virus had a fever upon testing.

The hospital also found one woman who initially tested negative for SARS-CoV-2, the severe acute respiratory syndrome that causes Covid-19, later displayed symptoms postpartum. She was tested three days after the initial test and received positive results.

"Although this prevalence has limited generalizability to geographic regions with lower rates of infection, it underscores the risk of Covid-19 among asymptomatic obstetrical patients," the study explained in regards to its findings.

"Moreover, the true prevalence of infection may be underreported because of false negative results of tests to detect SARS-CoV-2."

Experts have yet to determine the risk Covid-19 could have for pregnant women and their newborn children, but some hospitals have sectioned off their labour and delivery unit to prevent the virus from impacting those groups.

No pregnant woman has died from the novel virus, based on reported global cases. But countries have reported newborns and young children contracting and dying from the virus, including the US and UK.

The study expressed the need for universal testing given how people can be "silent carriers" of the virus.

"The potential benefits of a universal testing approach include the ability to use Covid-19 status to determine hospital isolation practices and bed assignments, inform neonatal care, and guide the use of personal protective equipment," the study read.

"Access to such clinical data provides an important opportunity to protect mothers, babies, and health care teams during these challenging times."