Hepatitis B in Pregnancy
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Direct answer
Hepatitis B in pregnancy carries a risk of vertical transmission, which occurs mostly at delivery and depends chiefly on HBeAg status and maternal viral load. Newborns of HBsAg-positive mothers need hepatitis B immunoglobulin and vaccine within 12 hours of birth, which prevents most infections. Tenofovir is added for women with high viral load, usually from late pregnancy, and elective caesarean is not needed for hepatitis B alone.
What you must remember
- Screening: HBsAg is tested at booking; a positive result triggers HBeAg, HBV DNA and liver function tests.
- HBeAg status: HBeAg-positive mothers transmit far more often, with rates commonly quoted at 70 to 90 percent without prophylaxis.
- Route: Most transmission happens around delivery rather than in utero.
- Newborn prophylaxis: Hepatitis B immunoglobulin plus the first vaccine dose within 12 hours of birth, then the full vaccine series.
- Antiviral therapy: Tenofovir disoproxil fumarate is started for HBV DNA above about 200,000 IU/mL, usually from 28 to 32 weeks.
- Mode of delivery: Elective caesarean is not indicated solely to prevent transmission; vaginal birth is allowed if other obstetric indications permit.
- Breastfeeding: Allowed once the newborn has received immunoprophylaxis, and maternal tenofovir does not stop it.
A pathway from screening to the newborn
Management is driven by two numbers, the HBeAg status and the HBV DNA level, and by whether the newborn is protected in time. The steps below follow that order.
- Screen and stage: HBsAg is checked at booking; positive women have HBeAg, HBV DNA and liver tests to judge infectivity and liver disease.
- Assess liver health: Check ALT, bilirubin, platelets and ultrasound for cirrhosis or portal hypertension, because chronic disease changes the plan.
- Treat the mother if needed: Start tenofovir when HBV DNA is high, usually from 28 to 32 weeks, and review after delivery, since flares can occur postpartum.
- Immunise the newborn: Hepatitis B immunoglobulin and the first vaccine dose are given within 12 hours of birth, followed by the standard vaccine series.
- Test the infant later: Anti-HBs and HBsAg are checked after the series is complete, usually some months later, to confirm protection and exclude infection.
- Counsel on feeding and delivery: Breastfeeding is allowed once the infant is protected, and the mode of delivery follows obstetric indications.
Where the examiner tries to catch you
Questions test the HBeAg-based risk, the newborn bundle and the delivery decision.
- Trap: Giving vaccine alone to the newborn of an HBsAg-positive mother Correct: Immunoglobulin and vaccine are both given at birth, because the combination is far more effective than vaccine alone.
- Trap: Choosing elective caesarean to prevent hepatitis B transmission Correct: Caesarean does not prevent transmission in HBsAg-positive women, so it is not indicated for that reason alone.
- Trap: Assuming a high viral load always needs caesarean Correct: Antiviral therapy lowers viral load, and the mode of delivery follows obstetric indications rather than hepatitis B alone.
Frequently asked questions
What is the newborn prophylaxis for an HBsAg-positive mother?
The newborn of an HBsAg-positive mother receives hepatitis B immunoglobulin and the first dose of hepatitis B vaccine within 12 hours of birth. The vaccine series is then completed on schedule, and this combination prevents most infections.
Does HBeAg status affect vertical transmission of hepatitis B?
HBeAg status strongly affects vertical transmission, and HBeAg-positive mothers transmit far more often than HBeAg-negative mothers. Viral load is also a key determinant, which is why it guides the decision to start tenofovir in late pregnancy.
Which antiviral is used in pregnancy to lower hepatitis B viral load?
Tenofovir disoproxil fumarate is the antiviral most often used in pregnancy to lower hepatitis B viral load. It is started when HBV DNA is high, usually in the late second or third trimester, with the decision taken with hepatology input.
Is caesarean section needed to prevent hepatitis B transmission?
Caesarean section is not needed solely to prevent hepatitis B transmission, because prophylaxis at birth is effective. Delivery mode follows standard obstetric indications, and women on tenofovir can still deliver vaginally.