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BACKGROUND: Perinatal transmission of hepatitis B virus (HBV) is highly preventable by post-exposure prophylaxis (PEP) administered shortly after birth. Identifying HBV-infected pregnant women is the crucial first step for ensuring infants receive timely PEP. The Centers for Disease Control and Prevention (CDC) annually estimates births to HBV-infected women using maternal race and ethnicity-specific hepatitis B surface antigen (HBsAg) prevalences to guide CDC’s Perinatal Hepatitis B Prevention Programs (PHBPP). Immigration to the United States from HBV-endemic areas has been increasing, and literature suggests HBsAg prevalence among immigrants may reflect prevalence in country of birth rather than country of relocation. To better estimate births to HBV-infected women in the United States, we revised the CDC model to incorporate maternal country of birth.
METHODS: To estimate annual births to HBV-infected (defined as HBsAg-positive) women in the United States, natality data from CDC’s National Center for Health Statistics (NCHS) were assessed by maternal country of birth. US-born mothers were then stratified by race/ethnicity, and foreign-born mothers were stratified by geographical region. Subcategories were multiplied by HBsAg prevalences estimated from the National Health and Nutrition Examination Survey (NHANES) 2007-2012 or PHBPP data.
RESULTS: In 2013, an estimated 18,017 infants were born to HBV-infected women in the United States, representing 0.46% of overall births. Infants born to US-born mothers comprised 77.40% of overall births and 33.35% of estimated births to HBV-infected mothers while infants born to foreign-born mothers comprised 20.22% of overall births and 58.93% of estimated births to HBV-infected mothers. Among US-born mothers, HBsAg prevalence was lowest among those who were White, non-Hispanic (point: 0.03%, 95% CI: 0.01-0.10) and highest among mothers of Other/Unknown race/ethnicity (point: 1.89%, 95% CI: 0.79-4.48).
CONCLUSIONS: Compared with the previous CDC model, this revised model estimates approximately 7,300 fewer births to HBV-infected women. The model may underestimate births to HBV-infected women since it partly utilizes HBsAg prevalences determined from PHBPP, which likely do not identify all infected women. However, the revised model is advantageous in that it categorizes mothers by region of birth which allows for applying region-specific HBsAg prevalences to estimate at-risk infants. Despite probable underestimation, as global vaccine campaigns impact hepatitis B prevalence, the revised CDC model can be used as a framework to incorporate evolving HBV infection prevalence for women from different parts of the world.