Hepatitis B in Pregnancy

Question 1

Chronic Hep B

Answer 1

Persistence of HepB surface ag for >6/12 following primary infection

• The younger the individual at time of infection, the higher the risk of Chronic infection IE Perinatal infection has 90% risk of chronic infection

Question 2

MTCT

Answer 2

• high risk from asymptomatic mothers
• Increased risk if sAg and eAg positive: Transmission 95%
• usually at delivery
• Transplacental transmission: +/- 5%
  -sAg + and eAg -: 2-15% vertical transmission
• HBV DNA is a more sensitive test of viral activity
• Higher VL = Higher risk of transmission
• Outside of pregnancy: Interferon induces sustained remission
• Oral antiviral (Lamivudine) has been shown to prevent progression

Question 3

Management in pregnancy:

Answer 3

MDT referral and management
1. Assess and manage maternal risk:
- Test HBeAg/HBeAb/HBV DNA/LFTs
- Check Hepatitis C and HIV serology
- Referral to gastroenterologist/ID for assessment of need for treatment and hepatocellular carcinoma
- Educate on risks of chronic infection
* 25% lifetime risk of cirrhosis or HCC
* If cirrhosis present, risk of HCC 4% per year
- Perform LFTs once per trimester
- Observe for postpartum HBV flares
* Occur in 25%
* Increased risk if HBeAg positive and nulliparous

2. Assess and manage fetal risk
   - Risk of fetal transmission highest in labour and delivery
   - Antenatal transmission may occur in the setting of:
   * Invasive procedures
   o Higher risk with CVS and transplacental amniocentesis
   compared to routine amniocentesis
   o Counsel about risk when discussing invasive testing and assess whether NIPT may be a suitable alternative
   * Preterm labour or placental abruption
   - Reducing risk of perinatal transmission
   * Risk factors for transmission
   o HBeAg status
   - If positive, increased risk of transmission
   o Viral load
   - Test at booking and repeat in third trimester
   - Lowering viral load antenatally reduces
   perinatal transmission
3. Antiviral therapy
   o If high viral load in T3 offer antiviral therapy from
   30/40
   - RANZCOG guidelines define high viral load as >200,000IU/mL
   * Use this cut-off!
   - AS ID use 10 to power 7 IU/mL
   o Tenofovir, lamivudine or telbivudine appropriate
   options
   o Continue treatment until 6/52 postpartum
   o Observe for HBV flares after cessation
4. Intrapartum management
   - Caesarean section not shown to reduce transmission
   - Avoid FSE, FBS and ventouse delivery

5.* Postpartum management
o Infant post-exposure prophylaxis and immunisation
- Hepatitis B immunoglobulin at birth and HB
vaccination within 12/24 of birth
- Repeat HB vaccine at 2, 4 and 6/12
o Breastfeeding is recommended
o Follow-up
- Repeat infant serology and HBsAg at 9-12/40

6. Assess and manage contacts risk
   - Test partner and children if not already tested
   - Offer immunisation to contacts that have negative testing

Question 4

Management Potential HBV exposure during pregnancy

Answer 4

• Clinical Assessment
• Assess nature of exposure (transmission through sexual contact/blood exposure)
  o Urgent maternal serology
• HBsAb >10IU/mL
• Patient immune
• No further antenatal mx
• Routine immunisation of infant at 2, 4 and 6/12
• HBsAg <10IU/mL
• Mother at risk of infection
• Give HB vaccination and HVIg within 72 hours of exposure
• Repeat vaccination 1 and 6/12 later
• Repeat testing for HBsAg 3/12 later
• If becomes HBsAg positive, manage maternal disease (below) and fetal risk (as above)