The effect of body mass index on post-vaccination maternal and neonatal pertussis antibody levels.

The objective was to determine if there is an association between maternal body mass index (BMI) and maternal and neonatal pertussis antibody concentrations following vaccination. This is a nested cohort study of 123 women who received the Tdap vaccine during pregnancy. Women were stratified by BMI into three groups--normal, overweight, and obese, based on first trimester or pre-pregnancy BMI. Maternal and umbilical cord serum samples were tested for post-vaccination pertussis IgG antibody. The mean maternal pertussis antibody concentration was 167.5 U/mL for normal BMI (n=29), 169.8 U/mL for overweight BMI (n=54), and 175.5 U/mL for the obese BMI groups (n=40). The mean fetal pertussis antibody concentrations were 182.3 U/mL, 191.4 U/mL, and 197.7 U/mL for these groups respectively. Seroprotection was achieved in 89.7% of neonates (26/29) in the normal BMI group, 87.0% (47/54) in the overweight BMI group, and 97.5% (39/40) in the obese BMI group. None of these differences reached statistical significance. Maternal BMI does not affect the maternal or neonatal pertussis antibody response to the Tdap vaccine in women who receive the vaccine in pregnancy. Maternal BMI is unlikely to affect the neonatal protective effects of a standard dose of Tdap vaccine in pregnancy. PRéCIS: Maternal and umbilical cord antibody response to the pertussis vaccine is not affected by maternal body mass index.