RESUMO
AIM: To determine the perinatal transmission risk of hepatitis B virus (HBV) and the maternal characteristics influencing it. METHOD: During routine antenatal screening, women who tested positive for hepatitis B surface antigen (HBsAg) were identified and followed through pregnancy. Maternal and cord blood samples were obtained at delivery. The sera of each mother-baby pair were analyzed for HBsAg, HBeAg, HBeAb, HBsAb and HBcAb using an immunochromatographic 5-in-1 panel kit. Quantitative HBV-DNA was assessed using polymerase chain reaction technique. Intrauterine infection was defined when neonatal blood test positive for HBsAg positivity and/or HBV-DNA. Confidence level was set at 95% (p < 0.05). RESULTS: Of the 716 pregnant women screened 73 (10.2%) were HBsAg-positive. Fifty of these HBsAg-positive women completed the study. Intrauterine infections were detected in 36 (72%) newborns; of them only twelve (24%) had positive HBsAg whereas all of them (n = 36) neonates had detectable HBV-DNA (>100 copies/ml). High maternal HBV-DNA titre was associated with increased neonatal HBV-DNA titre (p = 0.001). Parity, maternal age, and mode of delivery showed no association with perinatal transmission. CONCLUSION: The risk of perinatal HBV transmission in this study was high. Perinatal transmission was associated with high maternal viremia. Appropriate prophylaxis for HBsAg-positive mothers and their newborns is advocated.