Role of caesarean section in prevention of mother-infant transmission of hepatitis B virus.

447 infants, born to mothers positive for hepatitis B e antigen and hepatitis B surface antigen (HBsAg), received hepatitis B immunisation. A higher rate of hepatitis B virus (HBV) infection was found at birth in infants delivered vaginally (96/385, 24.9%) than in infants delivered by caesarean section (6/62, less than 10%). At birth, serum HBV-DNA was detected in 13 of 67 infants delivered vaginally, but in none of 30 infants delivered by caesarean section. Caesarean section combined with hepatitis B immunisation is advisable in infants of mothers who are chronic HBsAg carriers with high serum HBV-DNA levels.