How should chronic hepatitis B be screened and managed in a pregnant woman, including timing of antiviral therapy (tenofovir disoproxil fumarate), criteria for treatment (high hepatitis B virus DNA load or hepatitis B e‑antigen positivity), and infant prophylaxis with hepatitis B vaccine and immune globulin?

Management of Chronic Hepatitis B in Pregnancy

All pregnant women should be screened for HBsAg at the first prenatal visit, and those with HBV DNA >200,000 IU/mL or who are HBeAg-positive should receive tenofovir disoproxil fumarate starting at 28–32 weeks gestation, with all infants receiving both hepatitis B vaccine and HBIG within 12 hours of birth. 1

Screening Protocol

• Universal HBsAg screening is mandatory at the initial prenatal visit for every pregnancy, regardless of prior vaccination status or previous negative results. 1, 2
• Measure HBV DNA and ALT levels at 26–28 weeks gestation in all HBsAg-positive women to identify candidates for antiviral prophylaxis and assess maternal liver disease activity. 1, 3, 4
• Repeat HBsAg testing at hospital admission when maternal status is unknown or if new risk factors emerge (injection drug use, multiple sexual partners, recent STI, HBsAg-positive partner). 3, 5

Common pitfall: Failing to check third-trimester viral load leads to missed opportunities for prophylaxis in high-risk women—this occurs in more than 50% of HBsAg-positive pregnant persons in the U.S. 6

Antiviral Therapy Indications and Timing

• Initiate tenofovir disoproxil fumarate (TDF) 300 mg daily at 28–32 weeks gestation when maternal HBV DNA exceeds 200,000 IU/mL (≈5.3 log₁₀ IU/mL) or when the mother is HBeAg-positive. 1, 3, 2
• TDF is the sole first-line agent for HBV treatment during pregnancy, with FDA safety data from ≥3,300 first-trimester exposures showing no increase in major birth defects compared to background rates. 3
• For women with advanced fibrosis, cirrhosis, or active hepatitis (elevated ALT), continue TDF throughout pregnancy regardless of viral load, as maternal health takes priority. 1, 4
• Women already on entecavir must be switched to TDF before or during pregnancy, because entecavir is Category C (teratogenic in animal studies) while TDF is Category B. 3, 4

The 2021 AASLD guideline emphasizes that antiviral therapy in the third trimester reduces MTCT by 70% compared to no therapy (7.5% vs. 27%), with TDF specifically reducing transmission from 18% to 5%. 1 A 2017 meta-analysis of 733 pregnancies confirmed TDF reduces infant HBsAg seropositivity by 77% (OR 0.23,95% CI 0.10–0.52). 7

Duration of Antiviral Therapy

• Continue TDF through 12 weeks postpartum for women who started prophylaxis during pregnancy to prevent postpartum hepatitis flares. 3
• Monitor ALT every 1–3 months for 6 months after TDF discontinuation, as hepatic flares occur in 3.5%–25% of women within the first 3 months after delivery or cessation of antiviral treatment. 1, 8

Delivery Management

• Vaginal delivery is the preferred mode for all HBsAg-positive mothers; cesarean section should follow standard obstetric indications only. 1, 3, 4, 2
• Cesarean delivery solely for HBV prevention is not recommended by AASLD, ACOG, or EASL guidelines, as appropriately administered infant immunoprophylaxis negates transmission risk regardless of delivery mode. 1, 3

Narrow exception: Elective cesarean may be considered only for Asian, HBeAg-positive women with viral loads >7 log₁₀ copies/mL (>6.14 log₁₀ IU/mL) who did not receive antiviral therapy—a meta-analysis of 11,144 pregnancies (18 studies from China) showed reduced transmission in this subgroup (pooled OR 0.42,95% CI 0.23–0.76). 3

Invasive Prenatal Testing

• Prefer non-invasive prenatal testing (NIPT) over amniocentesis in HBeAg-positive women or those with HBV DNA >5.3 log₁₀ IU/mL, as invasive procedures increase MTCT risk, particularly in highly viremic women (≥7 log₁₀ IU/mL). 1, 3
• If invasive testing is necessary, provide informed consent discussing transmission risks and consider earlier initiation of antiviral therapy, although data supporting this practice are limited. 1

Neonatal Immunoprophylaxis (Critical)

• All infants born to HBsAg-positive mothers must receive both hepatitis B vaccine and HBIG within 12 hours of birth, regardless of whether maternal antiviral therapy was given. 1, 3, 4, 2
• Complete the vaccine series with doses at 1 month and 6 months of age. 1
• Perform serologic testing for anti-HBs at 9–12 months to confirm successful immunization. 8

This dual prophylaxis reduces MTCT from >90% to 5–10% in high-risk mothers, though prophylaxis failure still occurs in up to 15% of pregnancies when maternal viral load at delivery is high. 1 The risk of MTCT is extremely rare (<0.04%) when HBV DNA is below 200,000 IU/mL at delivery. 1, 3

Critical pitfall: HBIG administered to the mother antenatally is ineffective and should never be done—it provides no benefit in preventing transmission. 3

Breastfeeding

• Breastfeeding is safe and should be encouraged for all HBV-infected mothers, including those receiving TDF, as tenofovir concentrations in breast milk are low (<0.01%) and do not increase infant risk. 1, 3, 4, 2
• Contraindications are limited to cracked or bleeding nipples in mothers with detectable HBV DNA and infants with oral ulcers. 3

The 2023 EASL guidelines state with 100% consensus that breastfeeding should not be discouraged. 3 Discouraging breastfeeding contradicts current evidence and represents a common error in practice. 4

Postpartum Follow-Up

• Refer all HBsAg-positive mothers to local Perinatal Hepatitis B Prevention Programs for coordinated case management and counseling on household transmission prevention. 3, 5
• Screen in every subsequent pregnancy, even if prior tests were negative or the mother was vaccinated, to avoid missed new infections. 3, 5
• For women who stop TDF postpartum, monitor closely for viral reactivation with ALT and HBV DNA testing every 1–3 months for 6 months. 3, 8

Vaccination for Susceptible Women

• Hepatitis B vaccination is safe during pregnancy and should be offered to all women without serologic evidence of immunity or documented vaccination history. 1, 2
• High-risk HBsAg-negative pregnant women without immunity should be vaccinated during pregnancy, including healthcare workers, sex partners of HBsAg-positive individuals, persons who inject drugs, women with multiple sexual partners or recent STI, and international travelers to endemic regions. 5, 8

Algorithm Summary

1. First prenatal visit: Screen all women for HBsAg (and anti-HBs, anti-HBc if not previously documented). 1, 2
2. If HBsAg-positive: Measure HBV DNA and ALT at 26–28 weeks gestation. 1, 3
3. If HBV DNA >200,000 IU/mL or HBeAg-positive: Start TDF 300 mg daily at 28–32 weeks. 1, 2
4. At delivery: Vaginal delivery per obstetric indications; administer infant vaccine + HBIG within 12 hours. 1, 3, 2
5. Postpartum: Continue TDF through 12 weeks; monitor ALT every 1–3 months for 6 months after stopping. 3, 8
6. Infant follow-up: Complete vaccine series; check anti-HBs at 9–12 months. 1, 8