Seroprevalence of hepatitis B infection during pregnancy and risk of perinatal transmission.

OBJECTIVES To investigate the seroprevalence of hepatitis B surface antigen (HBsAg) in pregnant women and possible risk factors for perinatal hepatitis B virus (HBV) transmission. METHODS Four thousand pregnant women were evaluated using history, examination, and test for serum HBsAg using commercial enzyme immunoassay kits. For HBsAg positive women, liver function tests and a test for hepatitis B e antigen (HBeAg) was done. HBV DNA analysis was done by polymerase chain reaction (PCR). RESULTS Of 4,000 women studied, 37 (0.9%) tested positive for HBsAg. Of these 37 women, 6 (16%) presented with acute hepatitis and 31 (84%) were asymptomatic. The highest HBsAg positivity rate was seen in the age group of 21-25 years (1.15%) followed by 26-30 years (0.86%). Assessment of risk factors revealed history of tattooing in 29/37 (78.4%) women. HBeAg was positive in 21 of 37 (56.8%) women. Of the 16 HBeAg negative women, 5 were positive for HBV DNA and anti-HBe antibody, 6 had only anti-HBe antibody and 5 had neither HBV DNA nor anti-HBe. Vertical transmission was seen in 65% (13/20) of babies born to mothers who were positive for HBeAg and HBV DNA. In contrast, it was only 9.1% (1/11) for babies born to mothers who were negative for both HBeAg and HBV DNA. Of the 25 babies delivered vaginally, 15 (60%) developed vertical transmission. None of the four babies delivered by elective cesarean section had evidence of vertical transmission. CONCLUSIONS Seroprevalence of HBsAg in antenatal women was found to be 0.9%. HBe-antigen and HBV DNA positivity was associated with a higher chance of vertical transmission.