What are the management and testing strategies for a Hepatitis B (HBV) surface antigen positive mother to prevent perinatal transmission?

Management of Hepatitis B Surface Antigen Positive Mothers to Prevent Perinatal Transmission

All HBsAg-positive pregnant women should receive comprehensive management including HBV DNA testing, possible antiviral therapy with tenofovir starting at 28-32 weeks gestation if viral load >200,000 IU/mL, and their infants must receive both hepatitis B vaccine and HBIG within 12 hours of birth to prevent perinatal transmission. 1

Screening and Testing Protocol

• All pregnant women must be screened for HBsAg during early prenatal care, regardless of previous vaccination or testing status 1
• Women not tested prenatally should be tested at admission for delivery 1
• For HBsAg-positive pregnant women:
  • Test HBV DNA level to guide antiviral therapy decisions 1
  • Check liver function tests (ALT/AST, bilirubin, albumin, prothrombin time) at baseline and each trimester 1
  • Determine HBeAg status if not already known (helps predict transmission risk) 1
  • Repeat HBV DNA quantification at 24-28 weeks of gestation to assess need for antiviral therapy 1

Antiviral Therapy Decision Algorithm

1. Initiate tenofovir disoproxil fumarate (TDF) if any of the following:

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

2. Timing and Duration:

   • Start at 28-32 weeks gestation 1
   • Continue until 12 weeks postpartum 1
   • Monitor for hepatic flares 3 months postpartum (occur in 3.5-25% of women) 1

Note: Entecavir is not recommended during pregnancy as it is classified as Pregnancy Category C with insufficient human data on safety 2

Infant Prophylaxis Protocol

1. For infants born to HBsAg-positive mothers:

   • Administer hepatitis B vaccine AND HBIG within 12 hours of birth 1
   • This combined passive-active prophylaxis is 85-95% effective in preventing perinatal HBV infection 1
   • Complete the full HBV vaccination series according to standard schedule 1

2. For infants born to mothers with unknown HBsAg status:

   • Administer hepatitis B vaccine within 12 hours of birth 1
   • Add HBIG as soon as possible (within 7 days) if mother tests positive for HBsAg 1

3. Post-vaccination testing:

   • Test infants born to HBsAg-positive mothers for HBsAg and anti-HBs at 9-15 months of age 1
   • This determines the success of prophylaxis 1

Delivery Considerations

• Cesarean section is NOT 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
• Ensure maternal HBsAg status is clearly documented in medical records and communicated to the delivery facility 1

Postpartum Care

• Refer HBsAg-positive mothers to appropriate case-management programs 1
• Reassess the need for long-term HBV treatment based on standard criteria 1
• Breastfeeding is safe and should not be discouraged for HBsAg-positive mothers 1
• Exception: Avoid breastfeeding if mothers with detectable HBV DNA have cracked nipples or if the infant has oral ulcers 1

Important Clinical Considerations

• The risk of mother-to-child transmission is negligible (0.04%) when maternal HBV DNA is <200,000 IU/mL 1
• Despite optimal prophylaxis, 1-9% of infants born to HBV-carrying mothers may still develop HBV infection 3
• Research suggests that yeast-recombinant vaccines may have better efficacy than plasma-derived vaccines, especially in preventing late onset infections 4
• Studies comparing different HBIG dosages (100 IU vs 200 IU) found similar efficacy in preventing perinatal transmission when combined with hepatitis B vaccine 5

By following this comprehensive protocol, the risk of perinatal HBV transmission can be significantly reduced, preventing chronic HBV infection in newborns and its associated long-term complications.