Objective:To observe effect of Zhixue Baotai Yin in maintaining pregnancy in early threatened abortion.Methods:HCG and LH were monitored dynamically in 243 cases of early threatened abortion with colporrhagia.They were randomly divided into a treatment group（n=126）and a control group（n=117）

and were respectively treated with Zhixue Baotai Yin and progesterone. Their therapeutic effects were compared.Results:97 cases were cured in the treatment group with the fetus-protective rate of 76.98%

and 51 cases in the control group with the fetus protective rate of 43.59%

with a significant difference between the two groups（P<0.01）.Of 52 cases with HCG and LH lower than normal value at same pregnancy stage in the treatment group

24 cases aborted

the abortion rate being 46.15% and of 49 cases in control group

45 cases aborted

the abortion rate being 91.84%. The abortion rate in the treatment group was significantly lower than that in control group（P<0.01）.Conclusion:Zhixue Baotai Yin in increasing hormone level

alleviating symptoms

strengthening constitution

protecting fetus and others is superior to progesterone;and dynamic monitor of HCG and LH can provide a basis for diagnosis of abortion due to hormone factors

treatment of protecting fetus and judgment of stopping pregnancy.