Christian LM, et al. – Authors designed this work to determine the effects of prior influenza virus vaccination on maternal and cord blood antibody levels in a cohort of pregnant women in the US. In this cohort of pregnant women, the previous year influenza vaccination predicted higher baseline antibody titers and decreased antibody responses at one month post–vaccination against all influenza strains. However, prior maternal vaccination did not significantly affect either maternal antibody levels at delivery or antibody levels transferred to the neonate.