Mother-to-child Transmission of Hepatitis B

In Hong Kong, mother-to-child transmission (MTCT) is the major route of transmission of hepatitis B.
Hepatitis B virus (HBV) can be transmitted from mothers with chronic hepatitis B (CHB) to their babies during normal spontaneous delivery or Caesarean section.
Up to 90% of newborn babies infected with HBV would develop CHB.
In 2023, about 2.4% of pregnant women had been infected with HBV in Hong Kong. All pregnant women have to receive blood testing for hepatitis B during antenatal check-ups, in order to know their own infection status of hepatitis B.
If appropriate measures are taken, MTCT of hepatitis B could be prevented.

Hepatitis B vaccine

Regardless of the hepatitis B status of mothers, all newborn babies should receive the birth dose of hepatitis B vaccination in hospital. Afterwards, they should receive the second and third dose of the vaccination at the age of one month and six months respectively.
After completing the three-dose course of vaccination, 90 - 95% of babies can produce adequate protective antibody to protect them from HBV infection.

Babies born to mothers with CHB must be given hepatitis B immunoglobulin within 24 hours after birth for immediate extra protection.

Babies born to mothers with CHB should receive post-vaccination serologic testing (PVST), which can determine whether the babies are protected from HBV infection.
PVST consists of blood tests on hepatitis B surface antibody (anti-HBs) and hepatitis B surface antigen (HBsAg). It assesses a baby's immune response to hepatitis B vaccination and hepatitis B infection status.
PVST is conducted at the age of 9-12 months after the 3-dose course of hepatitis B vaccination (or 1 - 2 months after completion of the final dose of the primary vaccination series if the hepatitis B vaccination is delayed).
With effect from January 2022, Maternal and Child Health Centres arrange serologic testing after hepatitis B vaccination for babies born to mothers infected with HBV in or after April 2021. For details of this initiative, please view the fact sheet and press release.
With effect from June 2022, PVST will also be arranged for babies born to mothers infected with HBV in or after October 2020 before the age of 24 months.

Pregnant women with high HBV viral load may use antivirals in last trimester to reduce the viral load and the risk of MTCT of HBV.
All public hospitals with obstetric services under the Hospital Authority provide antiviral treatment option for pregnant women with high HBV viral load.
Postnatal women have to continue medical assessment and management of hepatitis, to determine the need for continuing antiviral medication.
Please consult doctor for details on antiviral treatment.