When should the Tdap vaccine be administered during pregnancy?

The Tdap vaccine is recommended during pregnancy to help protect both the mother and the newborn from pertussis (whooping cough). The optimal timing for administering the Tdap vaccine is between 27 and 36 weeks of gestation, specifically around 27 to 36 weeks. This timing allows the mother to produce adequate antibodies, which can then be transferred to the fetus, providing the newborn with some passive immunity against pertussis during the early months of life when they are most vulnerable.

Administering the vaccine within this window maximizes the effectiveness of maternal antibody transfer while minimizing any risk of adverse effects during the later stages of pregnancy. Getting vaccinated later in pregnancy (beyond 36 weeks) or early in pregnancy (before 27 weeks) may not provide as effective an immune response, and the antibodies needed for the newborn could be insufficient.