A fetus can manufacture immune cells and antibodies in direct response to vaccine given to the mother during pregnancy, according to researchers studying flu shots.
Scientists had already established that a pregnant woman can pass along certain antibodies to her fetus and that those immune proteins can protect a baby for up to 6 months after birth. Other studies had found that a fetus can muster an immune response to an infection contracted by the mother. But there had been little evidence indicating that a fetus can generate immunity to a vaccine, says study coauthor Rachel L. Miller, an immunologist at Columbia University College of Physicians and Surgeons.
Miller and her colleagues obtained blood samples from 70 pregnant women who had agreed to receive a flu shot about 7 months into their pregnancies. The Centers for Disease Control and Prevention recommend that women get flu shots in either the second or third trimester of pregnancy.