Abstract: Objective：To investigate the clinical efficiency of aspirin, low molecular heparin, metacortandracin, and aspirin combined with low molecular heparin in patients with unexplained recurrent spontaneous abortion (URSA). Methods: A total of 1 013 women with URSA who accepted the artificial cycle freezing embryo transfer (FET) were enrolled from January 2014 to April 2018. 596 patients in the control group were not treated with the additional drugs besides the artificial cycle. 417 patients treated with the additional drugs from the menstruation end to the 12 weeks of pregnancy in the experimental group were divided into four subgroups (aspirin, low molecular heparin, metacortandracin and aspirin combined with low molecular heparin). F test and χ2 test were used to analyze the differences in the biochemical pregnancy rate, clinical pregnancy rate, early abortion rate and parturition rate. Results: There were significant differences in the biochemical pregnancy rate and early abortion rate between the control group and the experimental group (P＜0.05). The biochemical pregnancy rate of aspirin subgroup, low molecular heparin subgroup and aspirin combined with heparin subgroup were significantly higher than that in the control group (P＜0.05). The early abortion rate of aspirin subgroup and the aspirin combined with heparin subgroup were significantly lower than that in the control group (P＜0.05). However, there were no significant differences in the clinical pregnancy rate and parturition rate between the two groups, and among those subgroups (P＞0.05). Conclusions: For those patients with URSA undergoing FET, the additional anticoagulant drugs besides the artificial cycle may improve the pregnancy outcomes. The low molecular heparin is helpful for embryo implantation, while aspirin may effectively reduce the rate of early abortion. Therefore, the additional treatment with anticoagulant drugs is worth recommending for those patients with URSA undergoing FET.

Key words: Abortion, habitual, Aspirin, Heparin, low-molecular-weight, Prednisone, Pregnancy rate, Premature birth, Parturition