The influence of maternal immunization on infant immune responses.

The vaccination of human mothers during pregnancy leads to transplacental transfer of antibody which can provide protection to the neonate during early life. This active transfer is a receptor-mediated event with preferential transport of antibody of the IgG1 and IgG3 subclasses via the FcR(n) receptor. The efficiency of trans-placental transfer is dependent on a range of factors including: placental integrity, the total IgG concentration in maternal blood, the type of vaccine, the timing of vaccine administration during gestation, the gestational age of the fetus at birth and the IgG subclass involved. The kinetics of maternal and infant serological responses has been extensively studied using Haemophilus influenzae b (Hib) vaccination as a model.