Estimating Annual Births to Hepatitis B Surface Antigen-Positive Women in the United States by Using Data on Maternal Country of Birth.

Objective: A national estimate of births to hepatitis B surface antigen (HBsAg)-positive women can help public health programs plan surveillance, educational, and outreach activities to improve identification and management of at-risk women and infants. Stratifying mothers by country of birth allows for the application of region-specific HBsAg prevalence estimates, which can more precisely estimate the number of at-risk infants. The objective of our study was to estimate the number of births to HBsAg-positive women in the United States with more granularity than previous models. Methods: We developed a model that incorporated maternal country of birth (MCOB) and updated HBsAg prevalence estimates. We assessed birth certificate data by MCOB, and we stratified US-born mothers by race/ethnicity, US territory-born mothers by territory, and non-US-born mothers by region. We multiplied and summed data in each subcategory by using HBsAg prevalence estimates calculated from the 2009-2014 National Health and Nutrition Examination Surveys or Perinatal Hepatitis B Prevention Program. We compared the findings of our MCOB model with a race/ethnicity model. Results: In 2015, an estimated 20 678 infants were born to HBsAg-positive women in the United States, representing 0.5% of all births. Births to US-born and non-US-born women comprised 77.2% and 21.5% of all births, respectively, and 40.1% and 57.9% of estimated births to HBsAg-positive women, respectively. The estimated contribution of births to HBsAg-positive women varied by MCOB region, from 4 (0.03%) infants born to women from Australia/Oceania to 5795 (28.0%) infants born to women from East Asia. Our MCOB model estimated 5666 fewer births to HBsAg-positive women than did the race/ethnicity model. Conclusions: As global vaccine programs reduce HBsAg prevalence, the MCOB model can incorporate evolving HBsAg prevalence estimates for women from various regions of the world.