Women contemplating pregnancy or seeking antenatal care should be made aware of the benefits of diagnosis of hepatitis B infection and management, and prevention strategies available to protect the infant from infection.39
The Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) guidelines state that all pregnant women should be screened using the HBsAg test.39 It is recommended that this take place at the first antenatal visit. If a woman is identified as HBsAg positive, further testing (HBeAg and HBV DNA) should be performed to determine the risk of transmission to the infant and the degree of infectivity in general, to inform clinical decision making.40
The risk of perinatal HBV transmission is determined by maternal hepatitis B viral factors; highly replicative infection characterised by high HBV DNA viral load and HBeAg positivity is associated with a higher risk of transmission. Timely administration of hepatitis B vaccination and hepatitis B immunoglobulin (HBIG) to the infant within 12 hours of birth will prevent most mother-to-child transmission. This strategy is highly effective, except in the setting of high maternal viral load (HBV DNA >200,000 IU/mL or log10 5.3 IU/mL), when motherto- child transmission can still occur in up to 10% of the vaccinated infants. Assessment of maternal HBV DNA early in the second trimester, and start of antiviral therapy at 28-30 weeks is recommended in the RANZOG guidelines.39 Women with a high viral load should receive specialist advice about the role of antiviral treatment during the third trimester to further reduce the risk of transmission. Current firstline choice for antiviral therapy is tenofovir, which has a favourable safety profile, high potency and low rates of resistance.41-47
Any woman diagnosed with hepatitis B infection in pregnancy should be assessed by an experienced clinician who will determine the phase and stage of her hepatitis B so that appropriate recommendations about treatment and monitoring can be made.
Jurisdictions should develop operational directives that support the RANZCOG guidelines through education, feedback on compliance and periodic auditing of antenatal medical records to provide evidence of recommended best practice.
HBsAg and anti-HBs levels can be measured in infants born to mothers with chronic HBV infection to allow identification of cases of mother-to-child transmission and vaccine failure. Follow-up testing should optimally be performed at 9-12 months of age, at least three months after completing the primary vaccine course, to confirm vaccine response and to avoid detection of passive anti-HBs from HBIG administered at birth or transient antigenaemia from vaccine.46 Recent Australian data has shown that mother-to-child transmission of HBV has not occurred in infants who received per protocol immunoprophylaxis with vaccine and HBIG if their mothers did not have a high viral load.47 Thus, while not harmful, testing these infants may be unnecessary and it is reasonable to focus serological follow-up efforts on those infants born to women with a high viral load. A positive HBsAg result from infant blood indicates infection and, in this case, the infant should be referred to a paediatric gastroenterologist, hepatologist or infectious diseases physician for further assessment.