To investigate the seroprevalence of hepatitis B surface antigen (HBsAg) in pregnant women and possible risk factors for perinatal hepatitis B virus (HBV) transmission.
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).
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.
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.