How do maternal vaccines protect newborn babies in the first months of life?

During pregnancy, antibodies made by the mother can pass through the placenta into the fetus, especially in the third trimester. These antibodies help protect newborns against infections such as influenza, pertussis, and sometimes RSV depending on the vaccine used. Maternal vaccination is a key strategy because some diseases are more dangerous in very young infants, who are too young for certain vaccines. After birth, breastfeeding may provide additional immune support through antibodies in milk, though it is not a substitute for vaccination. Maternal vaccines are used worldwide to reduce severe illness and complications in babies.