AIM: To evaluate the efficacy of interruption of intrauterine infection of HBV with HBIG in pregnant women with positive HBeAg and HBsAg.METHODS: A prospective randomized controlled trial was adopted. Sixty cases with positive HBeAg and HBsAg were coincident with the criteria of inclusion, and 8 cases were excluded. Fifty-two cases were analyzed (28 cases in trial group and 24 in control group). All cases in trial group received 200 IU HBIG intravenously every 4 wk for 3 times from the 28th wk. The cases of control group received placebo in the same way. All pregnant women were detected for HBeAg and HBV-DNA at the beginning of the trial and end of the trial (delivery). The cord blood of all newbs were collected for detecting HBeAg and HBV-DNA simultaneously.RESULTS: For investigation of HBeAg of newbs in trial group, 6 of 28 cases of newbs had positive HBeAg, the HBeAg positive rate being 21.4%, the total rate of 95% CI being 8%-41%. In control group, 19 of 24 cases of newbs had positive HBeAg, HBeAg positive rate was 79.2%, the rate of 95%CI being 5%-93%.By statistical analysis, χ2 = 17.26, P ＜ 0.01, RR = 0.27,95% CI (6.3 × 10-6, 8.6 × 10-5). For investigation of HBV-DNA of newbs in trial group, 7 of 28 cases of newbs had positive HBV-DNA, HBV-DNA positive rate being 25%, the total rate of 95% CI being 11%-45%. In control group, 20 of 24 cases of newbs had positive HBV-DNA, HBV-DNA positive rate was 83.3%, the total rate of 95% CI being 63%-95%. By statistical analysis, χ2 = 17.62, P ＜ 0.01, RR = 0.30, 95% CI (1.5 × 10-5, 1.7 × 10-4). The results indicated that there was significant difference in HBeAg positive rate and HBV-DNA positive rate of newbs between the two groups. In trial group, 7 of 28 newbs had HBV-DNA positive, but the HBV-DNA load of newbs was lower than that of their mothers. In control group, 20 of 24 newbs still had HBV-DNA positive, and the HBV-DNA load of newbs was close to those of their mothers. Statistical analysis indicated that there was no significant difference in HBVDNA load between postnatal women without HBIG intervention and their filial generations (T = 81.5, P ＞ 0.1).CONCLUSION: It is effective and safe to prevent intrauterine infection of HBV with HBIG from the 28th wk in pregnant women with positive HBeAg and HBsAg. In clinical application, those pregnant women with negative HBeAg and positive HBV-DNA also need to be interrupted by HBIG.