A study of pregnant women in Philadelphia found that most mothers with COVID-19 antibodies gave birth to newborns with those same antibodies, suggesting women can pass on some level of immunity through the umbilical cord. The research, published Friday in the journal JAMA Pediatrics, examined more than 1,500 women who gave birth at one hospital between April and August. In all, 83 of the women tested positive for COVID-19 antibodies, and 72 of their babies tested positive for antibodies through their cord blood, the researchers found. The women infected earlier in their pregnancies produced newborns with higher concentrations of antibodies.
"What we have found is fairly consistent with what we have learned from studies of other viruses," Scott Hensley, a microbiologist at the Perelman School of Medicine at the University of Pennsylvania and one of the senior authors of the study, told The New York Times. Human trials of COVID-19 vaccines did not include pregnant women, so there's little data to draw on, but in December, researchers reported that antibodies produced after influenza and pertussis (whooping cough) vaccines crossed the placenta easier than COVID-19 antibodies from natural infection.
"What we really want to know is, do antibodies from the vaccine efficiently cross the placenta and protect the baby, the way we know happens in influenza and pertussis," Dr. Denise Jamieson, an obstetrician at Emory University who studies COVID-19, told the Times. If the Philadelphia results are replicated in other studies, it could have implications not just for vaccinating pregnant women but also at what stage of the pregnancy to inoculate them.