How should hepatitis B be screened and managed during pregnancy, including antiviral therapy timing, delivery considerations, infant immunoprophylaxis, breastfeeding, and postpartum care?

Management of Hepatitis B in Pregnancy

All pregnant women should be screened for HBsAg in the first trimester, and those with HBV DNA >200,000 IU/mL should receive tenofovir disoproxil fumarate starting at 24-28 weeks gestation through 12 weeks postpartum, with all infants receiving both hepatitis B vaccine and HBIG within 12 hours of birth. 1

Screening Protocol

• Screen all pregnant women for HBsAg at the first prenatal visit (first trimester), regardless of prior vaccination status or previous negative tests. 1 This universal screening is essential because 30-40% of chronic HBV infections result from perinatal transmission. 1

• Retest at hospital admission if: 1

  • HBsAg status is unknown
  • The woman has new or ongoing risk factors (injection drug use, multiple sexual partners, HBsAg-positive partner, recent STI evaluation/treatment)
  • Clinical hepatitis is present

• For all HBsAg-positive women, measure HBV DNA and ALT levels at 26-28 weeks gestation to determine the need for antiviral prophylaxis. 1, 2 This timing is critical—failing to check viral load in the third trimester leads to missed opportunities for preventing transmission. 2, 3

Antiviral Therapy Decision Algorithm

Start tenofovir disoproxil fumarate at 24-28 weeks gestation if: 1

• HBV DNA >200,000 IU/mL (>5.3 log₁₀ IU/mL), OR
• HBeAg-positive status

Continue tenofovir throughout pregnancy (regardless of viral load) if: 1, 2

• Advanced fibrosis or cirrhosis is present
• Already on tenofovir treatment pre-pregnancy

Continue tenofovir through 12 weeks postpartum in women who started prophylaxis during pregnancy. 1 This extended duration helps prevent postpartum hepatitis flares. 4

Drug Selection

• Tenofovir disoproxil fumarate is the only first-line agent for HBV treatment in pregnancy. 1, 2, 3, 5 The FDA label confirms no increased risk of major birth defects (2.1% vs 2.7% background rate) based on over 3,300 first-trimester exposures. 5

• Switch from entecavir to tenofovir before or during pregnancy if the woman is already on treatment. 2, 3 Entecavir is Category C (animal teratogenicity) while tenofovir is Category B. 3

• Do NOT use lamivudine for long-term therapy due to high resistance rates. 2

Delivery Management

• Vaginal delivery is recommended; cesarean section should NOT be performed solely to reduce HBV transmission. 1, 2, 3 The mode of delivery should be based only on standard obstetric indications. 2

• Exception: Cesarean section may be considered only in Asian HBeAg-positive women with HBV DNA >7 log₁₀ copies/mL (6.14 log₁₀ IU/mL) who did not receive antiviral therapy during pregnancy. 1 However, this is a narrow exception and not routinely recommended.

Invasive Prenatal Testing

• Strongly prefer non-invasive prenatal testing over amniocentesis in HBeAg-positive women or those with HBV DNA >5.3 log₁₀ IU/mL due to high transmission risk. 1, 2

• Avoid chorionic villus sampling in HCV-infected women (similar precaution applies to high-risk HBV). 1

Neonatal Immunoprophylaxis

All infants born to HBsAg-positive mothers must receive BOTH: 1, 2, 3

• Hepatitis B vaccine (first dose) within 12 hours of birth
• Hepatitis B immune globulin (HBIG) 0.5 mL within 12 hours of birth (preferably immediately after physiologic stabilization)

Administer at separate injection sites. 6 The efficacy of HBIG decreases markedly if delayed beyond 48 hours. 6

Complete the vaccine series: Second dose at 1 month, third dose at 6 months. 1, 6

Perform postvaccination serologic testing at 9-12 months of age to confirm immunity. 1, 4

Critical Pitfall to Avoid

Do NOT administer HBIG to pregnant women antepartum—it is completely ineffective at reducing mother-to-child transmission regardless of maternal viral load. 1 HBIG is only given to the infant after birth. 6

Breastfeeding

Breastfeeding is safe and should be encouraged in all HBsAg-positive mothers, including those on tenofovir therapy. 1, 2, 3 The FDA label confirms tenofovir is present in breast milk but supports breastfeeding for HBV-infected mothers. 5

The only contraindications are: 1

• Cracked/bleeding nipples in mothers with detectable HBV DNA
• Oral ulcers in the infant

These are rare circumstances; routine breastfeeding should not be discouraged. 2, 3

Postpartum Monitoring

For women who received antiviral prophylaxis during pregnancy: 2, 4

• Monitor ALT every 1-3 months for 6 months postpartum to detect hepatitis flares after tenofovir discontinuation. 4
• Watch for viral reactivation in women who stop therapy postpartum. 2, 3

For all HBsAg-positive women: 1

• Refer to the jurisdiction's Perinatal Hepatitis B Prevention Program (PHBPP) for case management
• Provide counseling on preventing transmission to household contacts and sexual partners
• Ensure infant follow-up for vaccine series completion and serologic testing

Common Pitfalls and How to Avoid Them

1. Missing third-trimester viral load testing: Always measure HBV DNA at 26-28 weeks—this is when treatment decisions are made. 1, 2, 3

2. Giving HBIG to pregnant women: Never do this—it doesn't work. 1 HBIG is only for infants after birth. 6

3. Discouraging breastfeeding: Current evidence strongly supports breastfeeding safety with proper infant immunoprophylaxis. 1, 2, 3

4. Performing cesarean for HBV prevention: This provides no benefit and contradicts guideline recommendations. 1, 2, 3

5. Using entecavir instead of tenofovir: Tenofovir has superior safety data in pregnancy. 2, 3, 5

6. Forgetting to screen in subsequent pregnancies: Screen at every pregnancy, even if previously negative or vaccinated. 1

7. Inadequate postpartum monitoring: Hepatitis flares can occur after delivery and after stopping antivirals—monitor ALT regularly for 6 months. 4