American Board of Internal Medicine (ABIM) Certification Practice Exam

When should pregnant women receive the Tdap vaccine during each pregnancy?

1. Before 27 weeks gestation

2. Between 20 and 24 weeks gestation

3. Between 27 and 36 weeks gestation

4. After 36 weeks gestation

The correct answer is: Between 27 and 36 weeks gestation

Pregnant women should receive the Tdap vaccine between 27 and 36 weeks gestation to maximize the protection of both the mother and the newborn. This timing is recommended because it allows for the development of maternal antibodies that can be transferred to the fetus, offering the newborn some immunity against pertussis (whooping cough) during their early months of life, when they are most vulnerable to severe disease. Administering the vaccine within this gestational window is optimal because it aligns with the period when the mother's immune system can effectively respond to the vaccine, producing antibodies that will be passed to the baby. The goal is to provide the newborn with passive immunity before they are able to receive their own vaccinations, usually starting at 2 months of age. Receiving the Tdap vaccine before 27 weeks gestation may not allow adequate time for the maternal immune response needed to generate sufficient antibodies to be passed on. Timing it after 36 weeks could also mean that the vaccine's effectiveness and the transfer of antibodies to the newborn could be diminished, potentially leaving the infant more susceptible to infections during their critical early life. Thus, administering the Tdap between 27 and 36 weeks of gestation is strongly recommended to enhance the overall protection for the newborn.