Evidence Builds That Pregnant Women Pass Covid Antibodies to Newborns

One of the many big questions scientists are trying to untangle is whether people who get Covid-19 during pregnancy will pass on some natural immunity to their newborns.

Recent studies have hinted that they might. And new findings, published Friday in the journal JAMA Pediatrics, provide another piece of the puzzle, offering more evidence that Covid-19 antibodies can cross the placenta.

“What we have found is fairly consistent with what we have learned from studies of other viruses,” said Scott E. Hensley, an associate professor of microbiology at the Perelman School of Medicine at the University of Pennsylvania and one of the senior authors of the study.

Additionally, he added, the study suggests that women are not only transferring antibodies to their fetuses, but also transferring more antibodies to their babies if they are infected earlier in their pregnancies. This might have implications for when women should be vaccinated against Covid-19, Dr. Hensley said, adding that vaccinating women earlier in pregnancy might offer more protective benefits, “but studies actually analyzing vaccination among pregnant women need to be completed.”

In the study, researchers from Pennsylvania tested more than 1,500 women who gave birth at Pennsylvania Hospital in Philadelphia between April