Maternal immunization

Maternal immunization can enhance passive immunity of infants to pathogens that cause life-threatening illnesses. In most instances, immunization duri ng pregnancy will provide important protection for the woman as well as for her offspring. The tetanus toroid and influenza vaccines are examples of v accines that provide a double benefit. Other vaccines under evaluation incl ude those for respiratory syncytial virus, pneumococci, group B streptococc i, and Haemophilus influenzae type b. Although most IgG antibody crosses th e placenta in the third trimester, the process is time-dependent, dictating that immunization should be accomplished ideally at least 6 weeks prior to delivery. IgG1 antibodies are transferred preferentially. Maternal immuniz ation has not interfered with active immunization of the infant. Inactivate d vaccines administered in the third trimester of pregnancy pose no known r isk to the woman or to her fetus.