Babies grow at the same rate regardless of whether their pregnant or breastfeeding mom gets the tetanus, diphtheria, and pertussis (Tdap) vaccine, according to new research published this week in the journal Vaccine.
The findings, which analyzed 42,758 electronic health records, are reassuring, write the authors, as they provide real-world evidence that maternal Tdap vaccination is safe for babies. The authors say the results can help parents decide whether to get a vaccine that protects against three potentially deadly bacterial infections.
Additionally, the study found that maternal Tdap vaccination, either before or after birth, had no bearing on the frequency of emergency room visits for babies during their first 6 months of life. However, there was a 7% increase in outpatient visits (which include well-child appointments, video visits, and trips to urgent care clinics) among babies whose mothers were vaccinated. The researchers theorize this finding is because parents who opted to vaccinate are more likely to seek medical care.
Last year 16 in US died of pertussis, including 6 babies
Just 55.4% of pregnant women in the United States receive the Tdap vaccine, according to a 2023 analysis from the Centers for Disease Control and Prevention (CDC). The CDC recommends the Tdap shot from 27 to 36 weeks of gestation, as this lowers the risk of pertussis, or whooping cough, for infants under two months of age by 78%.
CDC data show that 16 people died of pertussis in 2025; six were under 1 year of age. There were also 28,783 hospitalizations.