Can hepatitis B (HBV) transmit to the baby?

Hepatitis B Transmission to Babies

Yes, hepatitis B virus (HBV) can transmit from mother to baby, primarily during delivery, with rare instances of in utero transmission. 1

Risk of Mother-to-Child Transmission

The risk of perinatal HBV transmission varies significantly based on maternal factors:

• For mothers positive for both HBsAg and HBeAg: 70-90% risk of transmission without prophylaxis 1
• For mothers positive for HBsAg but negative for HBeAg: <10% risk of transmission without prophylaxis 1
• With proper immunoprophylaxis: Risk reduced to 0.7-1.1% 1
• High maternal viral load: Remains the most significant risk factor for transmission despite immunoprophylaxis 1, 2

When Transmission Occurs

• Primary transmission timing: Most cases occur during delivery 1
• In utero transmission: Rare but possible 1
• Postpartum exposure: Children not infected at birth remain at risk through household contact with infected mothers (38% may become infected by age 4 years) 1

Factors Increasing Transmission Risk

• High maternal viral load: Especially ≥200,000 IU/mL 1
• HBeAg positivity: Strong marker for high infectivity 1, 2
• Young maternal age: Associated with higher transmission rates 2
• Asian/Pacific Islander race: Higher risk of transmission 2
• Inadequate infant vaccination: Receiving <3 HepB vaccine doses increases risk 2

Prevention of Transmission

The most effective prevention strategy is a combination approach:

1. Universal screening of all pregnant women for HBsAg 1

2. Immunoprophylaxis for exposed infants:

   • Hepatitis B vaccine at birth
   • Hepatitis B immune globulin (HBIG) within 12 hours of birth
   • Completion of the full HepB vaccine series 1, 3

3. Maternal antiviral therapy during pregnancy for women with high viral loads (>200,000 IU/mL) 1

4. Breastfeeding considerations:

   • Breastfeeding is generally safe and should not be discouraged 1
   • Exception: If mother has cracked nipples or infant has oral ulcers and mother has detectable HBV DNA 1

Effectiveness of Prevention

• Combined approach (vaccine + HBIG): 85-95% effective in preventing chronic HBV infection 3
• Vaccine alone: 70-90% effective 3
• HBIG alone: Only about 50% effective 3

Important Clinical Considerations

• Cesarean section is generally not recommended solely to prevent HBV transmission unless the mother has a high viral load (>10^7 copies/mL) and has not received antiviral therapy during pregnancy 1

• Chronic HBV infection acquired in infancy has severe long-term consequences:

  • 90% risk of developing chronic infection when infected as a newborn 1
  • 25% risk of premature death from cirrhosis or liver cancer 1

• Infants born to mothers with viral loads in the highest deciles are at greatest risk of breakthrough infection despite immunoprophylaxis 2

The comprehensive prevention strategy of universal maternal screening, timely infant immunoprophylaxis, and maternal antiviral therapy when indicated has dramatically reduced perinatal HBV transmission rates and should be implemented for all pregnancies.