Abstract: Objective：To analyze the effect of early anticoagulation intervention on pregnancy outcome in patients with high D-dimer before freezing embryo transfer (FET). Methods：A total of 89 patients undergoing FET were included in the present study. The level of D-dimer on the day before FET was measured. Those patients with high D-dimer (more than 0.5 μg/mL) were randomly divided into two groups: the treatment group (43 patients) and the control group (46 patients). Patients in the treatment group were treated with low-dose aspirin or low-molecular-weight heparin sodium, while patients in the control group were not treated. The D-dimer level, implantation rate, clinical pregnancy rate and early abortion rate were compared between the two groups. Results：There were no significant differences in D-dimer concentration, implantation rate and clinical pregnancy rate between the two groups (P＞0.05). However, the abortion rate in the treatment group was significantly lower than that in the control group (P＜0.05). Conclusions：Early anticoagulation therapy with low dose aspirin or low molecular weight heparin in those patients with the high level of D-dimer before FET can improve the pregnancy outcome.

Key words: Fertilization in vitro, Embryo transfer, Fibrin fibrinogen degradation products, Aspirin, Heparin, low-molecular-weight, Pregnancy outcome, Therapy