Pregnant women are at risk for infection and may have significant morbidity or mortality. Influenza, pertussis, zika, and cytomegalovirus produce mild or asymptomatic illness in the mother, but have profound implications for her fetus. Maternal immunization can prevent or mitigate infections in pregnant women and their infants. The Advisory Committee of Immunization Practices recommends 2 vaccines during pregnancy: inactivated influenza, and tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis during pregnancy. The benefits of MMR, varicella, and other vaccines are reviewed. Novel vaccine studies for use during pregnancy for prevention of illness are explored.