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 (H bsAg) and antibody (HbsAb) negative on initial prenatal screen, were analyz ed 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 qualitat ive enzyme-linked immunosorbent assay analysis. The women were grouped by m aternal age (less than 25 years or at least 25 years), smoking history, mat ernal weight, body mass index (BMI) (less than 30, at least 30, less than 3 4, or at least 34), number of vaccinations received, race-ethnicity, gestat ional age at vaccination, and vaccination-to-rescreening interval. Data wer e compared by t test, chi(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. Logisti c regression analysis for predicting failure of seroprotective response aft er 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 infl uences on the efficacy of hepatitis B vaccination in pregnant women. (Obste t Gynecol 1999;93: 983-6. (C) 1999 by The American College of Obstetricians and Gynecologists.).