What is the management and testing for a Hepatitis B (HBV) surface antigen positive pregnant patient to prevent perinatal transmission?

Management of Hepatitis B Surface Antigen Positive Pregnant Women to Prevent Perinatal Transmission

All pregnant women who test positive for HBsAg should receive HBV DNA testing to guide antiviral therapy decisions, and their infants must receive both hepatitis B vaccine and HBIG within 12 hours of birth to prevent perinatal transmission. 1

Prenatal Testing and Monitoring

• Initial Testing:

  • All pregnant women should be tested for HBsAg during early prenatal care (first trimester), regardless of previous vaccination or testing status 2, 1
  • Women not tested prenatally should be tested at admission for delivery, especially those with high-risk behaviors or clinical hepatitis 2
  • All HBsAg-positive pregnant women should undergo HBV DNA quantification to guide antiviral therapy decisions 2, 1

• Additional Testing for HBsAg-Positive Women:

  • Liver function tests (ALT/AST, bilirubin, albumin, prothrombin time) at baseline and each trimester 1
  • HBeAg status if not already known (helps predict transmission risk) 1
  • Repeat HBV DNA quantification at 24-28 weeks gestation 1

Antiviral Therapy During Pregnancy

• Indications for Antiviral Therapy:

  • HBV DNA >200,000 IU/mL (primary indication) 2, 1
  • HBeAg-positive status with high viral load 1
  • Advanced fibrosis or cirrhosis (regardless of viral load) 1

• Antiviral Regimen:

  • Preferred agent: Tenofovir disoproxil fumarate (TDF) - FDA pregnancy category B 2, 1
  • Start at 28-32 weeks gestation 1
  • Continue until 12 weeks postpartum 1
  • Monitor for hepatic flares postpartum (occur in 3.5-25% of women) 1

Infant Management at Birth

• For Infants Born to HBsAg-Positive Mothers:

  • Administer both hepatitis B vaccine (first dose) AND HBIG (0.5 mL) within 12 hours of birth, at different injection sites 2, 1
  • Complete the full hepatitis B vaccine series according to the recommended schedule 2
  • The final dose should not be administered before age 24 weeks (164 days) 2
  • For preterm infants weighing <2,000 g, the initial vaccine dose should not be counted as part of the series; give 3 additional doses beginning at age 1 month 2

• For Infants Born to Mothers with Unknown HBsAg Status:

  • Administer hepatitis B vaccine within 12 hours of birth 2, 1
  • Test mother for HBsAg immediately 2
  • If mother tests positive, administer HBIG to infant as soon as possible (within 7 days of birth) 1

Follow-up Testing and Monitoring

• Infant Testing:

  • Test for HBsAg and anti-HBs at 9-15 months of age (after completion of vaccine series) 2, 1
  • Testing should not be performed before age 9 months to avoid detection of anti-HBs from HBIG administered during infancy 2

• Maternal Follow-up:

  • Refer all HBsAg-positive pregnant women to appropriate case-management programs 2, 1
  • Provide counseling regarding:
    • Modes of HBV transmission
    • Perinatal concerns
    • Prevention of HBV transmission to contacts
    • Medical evaluation and possible treatment of chronic hepatitis B 2, 1

Important Considerations

• Breastfeeding:

  • Breastfeeding is safe for HBsAg-positive mothers and should not be discouraged 1
  • Exception: Avoid if mothers have cracked nipples or if infants have oral ulcers 1

• Delivery Method:

  • Cesarean section is not specifically recommended solely to prevent HBV transmission 1
  • Vaginal delivery is appropriate for HBsAg-positive women, even with high viral loads, if they received antiviral prophylaxis 1

• Communication:

  • Ensure maternal HBsAg status is clearly documented and communicated to the delivery facility 2, 1
  • A copy of the original laboratory report indicating HBsAg-positive status should be provided to the hospital where delivery is planned 2

Efficacy of Prevention Strategies

• Combined passive-active prophylaxis with HBIG and hepatitis B vaccine is 85-95% effective in preventing perinatal HBV infection 1
• The risk of mother-to-child transmission is negligible (0.04%) when maternal HBV DNA is <200,000 IU/mL 1
• Antiviral therapy during pregnancy further reduces the risk of transmission in women with high viral loads 3

This comprehensive approach to managing HBsAg-positive pregnant women and their infants is critical for preventing perinatal transmission of HBV, which causes the highest chronic carrier rate (>85%) with subsequent risk of chronic liver disease and hepatocellular carcinoma 4.