BETHESDA, Md. — The third and final trimester of pregnancy is a critical time for mother and child. No parent wants anything to happen that could compromise the delivery. So what happens if the mother-to-be contracts COVID-19? Researchers with the National Institutes of Health are putting some concerns to rest, finding that pregnant women are not likely to pass the coronavirus to their babies during this time.

Researchers tested 64 pregnant women who contracted SARS-CoV-2, the virus which causes COVID-19, and the results reveal none of them gave birth to a child testing positive for the illness. None of the virus made its way into the patient’s bloodstream or placenta. Researchers did however find the virus in the fluid in the expecting mother’s lungs, nose, and throat.

The research team cautions their results don’t guarantee women can’t transfer COVID to their infants, since the study size only examined 64 women in their third trimesters. Regardless, scientists say the findings are positive when it comes to virus transmission.

“This study provides some reassurance that SARS-CoV-2 infections during the third trimester are unlikely to pass through the placenta to the fetus, but more research needs to be done to confirm this finding,” says Dr. Diana Bianchi, director of the National Institute of Child Health and Human Development (NICHD), in a media release.

Antibody surprises during pregnancy

Among the expecting moms testing positive for COVID-19, 23 were asymptomatic, 22 had mild symptoms, seven had a moderate illness, 10 had a severe infection, and two became critically ill.

Study authors also examined another 63 pregnant women who did not have coronavirus and 11 women with COVID who were not pregnant for comparison. Researchers discovered the risk of reduced blood flow in the placenta is higher for women who suffer the most severe cases of COVID-19.

The team noticed lower than expected levels of protective antibodies in umbilical cord blood, but strangely much higher levels of influenza-specific antibodies. Researchers believe this may come from flu vaccinations, suggesting that COVID antibodies do not pass through the placenta as well as some others. The results also show only a very low level of COVID antibodies made it to the unborn child, raising more questions.

Study authors note it will be important to figure out why these maternal antibodies are less likely to reach the placenta and whether this reduced antibody transfer leaves newborns more vulnerable to the SARS-CoV-2 virus.

Researchers add it will also be important to determine how lower levels of maternal SARS-CoV-2 antibodies may impact babies born premature. The study finds COVID-19 may increase the risk of preterm labor.

The findings appear in the journal JAMA Network Open.

SWNS writer William Janes contribute to this report.

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