Third-Trimester Maternal Vaccination Against Pertussis and Pertussis Antibody Concentrations.

OBJECTIVE: To compare pertussis antibody concentrations in maternal venous serum (at the time of delivery) and umbilical cord arterial serum among women vaccinated with the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine from either 27-30 6/7 weeks of gestation or from 31-35 6/7 weeks of gestation. METHODS: We conducted a prospective cohort study of pregnant women divided into two groups based on when Tdap was administered: 27-30 6/7 weeks of gestation and 31-35 6/7 weeks of gestation. Paired maternal and umbilical cord samples were obtained at the time of delivery to determine immunoglobulin G (IgG) concentrations to pertussis toxin and pertactin. RESULTS: Eighty-eight pregnant women were enrolled. Cord serum pertussis toxin IgG concentrations were approximately twice maternal serum pertussis toxin IgG concentrations (91.6 vs 48.6 enzyme-linked immunoassay [ELISA] units/mL, P CONCLUSION: Maternal vaccination against pertussis between 27 and 36 weeks of gestation was associated with a high percentage of newborns with antibody concentrations conferring protection and did not vary by gestational age at vaccination