In a pregnant woman with chronic hepatitis B infection, what delivery route is recommended to minimize mother‑to‑child transmission?

Mode of Delivery for Hepatitis B-Positive Pregnant Women

Vaginal delivery is recommended for most pregnant women with chronic hepatitis B infection, as cesarean section does not reduce mother-to-child transmission when appropriate neonatal immunoprophylaxis is provided. 1

General Recommendation for Mode of Delivery

Cesarean section is not recommended to reduce the risk of HBV mother-to-child transmission in HBsAg-positive women. 1 The delivery route should be determined based solely on standard obstetric indications, not on maternal HBV status. 2, 3

The risk of mother-to-child transmission is negligible (0.04%, 95% CI 0.00–0.25) when maternal HBV DNA is <200,000 IU/ml (5.30 log₁₀ IU/ml), regardless of delivery mode and with proper infant immunoprophylaxis. 1

Exception: High-Risk Asian Women

Cesarean section may be considered only in Asian HBeAg-positive women with very high HBV DNA levels (>7 log₁₀ copies/ml or 6.14 log₁₀ IU/ml) who have NOT received antiviral therapy during pregnancy. 1, 2

This is a narrow exception based on:

• A meta-analysis of 19 studies (18 from China) involving 11,144 HBV-positive pregnant women showed cesarean section reduced transmission risk in this specific population (pooled OR 0.42,95% CI 0.23–0.76). 1
• However, this recommendation applies only when antiviral prophylaxis was not given during pregnancy. 1, 2

Why This Exception Exists

The data supporting cesarean section comes predominantly from Chinese populations studied before widespread use of third-trimester antiviral prophylaxis. 1, 4 One study showed elective cesarean section reduced vertical transmission from 3.4% (vaginal delivery) to 1.4% (P < 0.032) in highly viremic mothers. 4

Important caveat: Women with HBV DNA <1,000 copies/ml did not transmit infection regardless of delivery method. 4

The Preferred Strategy: Antiviral Prophylaxis

Rather than relying on cesarean section, the evidence-based approach is to initiate tenofovir disoproxil fumarate at 24-28 weeks gestation in women with HBV DNA >200,000 IU/ml. 2, 3 This intervention:

• Markedly reduces viral load before delivery 2
• Eliminates the need for cesarean section in most cases 2
• Is the first-line agent with extensive safety data (>3,300 first-trimester exposures showing no increased birth defects). 2

Essential Neonatal Immunoprophylaxis

All infants born to HBsAg-positive mothers must receive both hepatitis B vaccine AND hepatitis B immune globulin (HBIG) within 12 hours of birth, regardless of delivery mode or maternal antiviral therapy. 2, 3 This dual prophylaxis reduces transmission from >90% to 5-10% in high-risk mothers. 1

Common Pitfalls to Avoid

• Do not perform elective cesarean section solely for HBV prevention in women who received appropriate antiviral prophylaxis. 2 The mode of delivery should follow obstetric indications. 2, 3
• Do not omit third-trimester HBV DNA testing (at 26-28 weeks). 2 This identifies candidates for antiviral prophylaxis and eliminates most indications for cesarean section. 2
• Urgent/emergency cesarean section provides no benefit over vaginal delivery for HBV transmission prevention (4.2% vs 3.4%, P = 0.593). 4 Only elective cesarean section before labor/membrane rupture showed potential benefit in older studies. 4, 5

Algorithm for Decision-Making

1. Measure HBV DNA at 26-28 weeks gestation in all HBsAg-positive women. 2, 3

2. If HBV DNA >200,000 IU/ml or HBeAg-positive:

   • Start tenofovir at 24-28 weeks 2
   • Plan vaginal delivery based on obstetric indications 2
   • Ensure neonatal immunoprophylaxis within 12 hours 2

3. If HBV DNA >7 log₁₀ copies/ml (6.14 log₁₀ IU/ml) AND patient is Asian, HBeAg-positive, AND did not receive antiviral therapy:

   • Consider elective cesarean section 1
   • Still provide neonatal immunoprophylaxis within 12 hours 2

4. All other cases: Vaginal delivery per obstetric indications. 1, 2