Pregnant women pass along protective COVID antibodies to their babies: ACOG study

In addition, the vast majority of the babies born to these women--78 percent--had detectable antibodies in their umbilical cord blood. There was no evidence that any of the infants had been directly infected with the virus and all were COVID negative at the time of birth, further indicating that the antibodies had crossed the placenta--the organ that provides oxygen and nutrients to a growing baby during pregnancy--into the fetal bloodstream. Newborns with symptomatic mothers also had higher antibody levels than those whose mothers had no COVID symptoms.

This data implies that pregnant women could pass along vaccine-generated antibodies in the same way, potentially shielding both mother and child from future infection. However it is not yet known exactly how protective these antibodies might be, or how long that protection might last. Dr. Laura Riley, chair of the Department of Obstetrics and Gynecology at Weill Cornell Medicine, obstetrician and gynecologist-in-chief at NewYork-Presbyterian/Weill Cornell and one of the study's co-authors, is still advising pregnant patients who decide to get vaccinated to continue to follow current safety guidelines to prevent the spread of the disease. Dr. Riley, Dr. Yang and their colleagues are leading follow-up investigations that are currently enrolling pregnant women who receive the vaccine, as well as vaccinated mothers who are breastfeeding, to assess the antibody response in those groups after vaccination. That information could help guide maternal vaccination strategies moving forward.

"The $1 million question is: Will the group of women who are now being vaccinated get the same type of protection? We don't know that yet," Dr. Riley said. "Getting those answers is going to be really important."