Hepatitis B vaccination in pregnancy: factors influencing efficacy

Objective: To determine seroprotective antibody response after hepatitis B vaccination during pregnancy and to assess factors influencing the rate of maternal seroprotection. Methods: Records of 80 healthy gravidas who elected hepatitis B vaccination during pregnancy, after being identified as hepatitis B surface antigen (HbsAg) and antibody (HbsAb) negative on initial prenatal screen, were analyzed retrospectively. Each gravida was begun on a series of three recombinant hepatitis B vaccines at 0, 1, and 6 months. At 36–40 weeks’ gestation, all gravidas were rescreened for seroprotective levels of HbsAb using qualitative enzyme-linked immunosorbent assay analysis. The women were grouped by maternal age (less than 25 years or at least 25 years), smoking history, maternal weight, body mass index (BMI) (less than 30, at least 30, less than 34, or at least 34), number of vaccinations received, race-ethnicity, gestational age at vaccination, and vaccination-to-rescreening interval. Data were compared by t test, χ 2 test, or Fisher exact test. Stepwise logistic regression analysis was done. Results: At rescreening, 39 (49%) of the 80 women had seroprotective HbsAb conversion. After two vaccinations, obese women (BMI at least 30) ( P = .04), women at least 25 years old ( P = .04), and women with smoking histories ( P = .005) were significantly less likely to respond to the vaccine. Logistic regression analysis for predicting failure of seroprotective response after two vaccinations showed significantly increased odds for severe obesity with BMI at least 34 (odds ratio [OR] 16.2; 95% confidence interval [CI] 1.7, 154.7), smoking history (OR 7.5; 95% CI 2.0, 27.7), and age at least 25 years (OR 3.9; 95% CI 1.1, 14.4). Conclusion: Maternal obesity, advancing age, and smoking have negative influences on the efficacy of hepatitis B vaccination in pregnant women.