RESUMO
<p><b>OBJECTIVE</b>To study the risk factors of hepatitis B virus (HBV) intrauterine infection.</p><p><b>METHODS</b>Risk factors of HBV intrauterine infection were analyzed by nested case control study.</p><p><b>RESULTS</b>Data from univariate analysis revealed that risk factors of HBV intrauterine infection were positive results on HLA-DR3 (OR = 4.71, 1.62-13.66), HBV DNA (OR = 6.59, 2.72-15.97) and HBeAg (OR = 4.53, 1.93-10.64) in pregnant women, HLA-DR3 (OR = 3.91, 1.18-12.94) in newborn, HLA-I) R3 (OR = 5.96, 1.14-31.15) both in pregnant women and her newborns and HBV infection in placentas (OR = 2.51,1.12-5.60). Results from Multivariate unconditional logistics regression analysis showed that the risk factors of HBV intrauterine infection were positive in both HLA-DR3 (OR = 4.65, 1.44-15.05) and HBV DNA (OR = 6.56, 2.65-16.23) in pregnant women. However, there was no interaction between the two factors. The exposure rate of other factors did not reveal the difference in the two groups. With the increase of HBV DNA in pregnant women, the risk of HBV intrauterine infection was rising (chi2 = 16.74, P < 0.05).</p><p><b>CONCLUSION</b>Risk factors of HBV intrauterine infection were HLA-DR3 positive and HBV DNA positive in pregnant women but there was no interaction between the two factors. The risk of HBV intrauterine infection was increased along with the increase of HBV DNA in pregnant women.</p>