Study: Mother's may pass Covid-19 antibodies to newborns

A mother's Covid-19 antibodies can cross the placenta, potentially protecting her fetus from infection, researchers reported on Friday in Jama Pediatrics. 

Several weeks after the mother's infection begins, antibody levels in umbilical cord blood "can be as high as - or even higher - than the levels in maternal blood," said study leaders Dr Karen Puopolo and Dr Scott Hensley of the University of Pennsylvania, reports Reuters.

Researchers at Children's Hospital of Philadelphia and Pennsylvania Hospital tested more than 1,700 pregnant women for Covid-19 antibodies, reports United Press International (UPI).

Once these mothers delivered their babies, the researchers tested blood samples collected from the umbilical cords for Covid-19 antibodies.

In their study, out of 83 women who had Covid-19 antibodies when they gave birth, 72 of their newborns also had antibodies but no evidence of direct infection. 

"Our work shows that maternal antibodies to [Covid-19] can efficiently cross the placenta, and therefore demonstrates the potential for such maternally derived antibodies to provide neonatal protection from infection," Puopolo told UPI.

"To put it simply, when a woman makes antibodies to [the] virus during pregnancy, those antibodies are transferred to her baby," said Puopolo.

"It is reassuring that maternal infection, whether symptomatic or asymptomatic, results in sufficient antibody production for an efficient transplacental antibody transfer to newborns of infected mothers," said Dr Flor Munoz of Baylor College of Medicine in an editorial published with the study.

It is possible antibodies created via a vaccine could have the same effect, Munoz noted. 

Transfer of substances in the mother's blood to the fetus starts around 17 weeks of gestation, Munoz said, which suggests that "maternal vaccination starting in the early second trimester ... might be optimal to achieve the highest levels of antibodies in the newborn."