Objective There are few studies on the application of low molecular weight heparin (LMWH) in the therapy of women with recurrent spontaneous abortion (RSA) pregnant by assisted reproductive technology (ART).The article aimed to explore the clinical research of LMWH in therapy of women with RSA pregnant by ART.Methods 126 women with RSA pregnant by ART were enrolled and they were diagnosed and treated in Reproductive Medicine Center in the Affiliated Hospital of Guangdong Medical University from January 2010 to February 2016.According to the patient′s agreement on LMWH treatment, 60 patients in agreement with LMWH treatment were divided into 2 groups: LMWH+IUI group(n=30) and LMWH+ IVF-ET group(n=30).66 patients in disagreement with LMWH treatment were also divided into 2 groups: IUI group(n=32) and IVF-ET group(n=34).Comparison was made in patients from 4 groups concerning pregnancy success rate, live birth rate, pregnancy time involving RSA and incidence of pregnancy complications.At the same time, the occurrence of adverse reactions during the use of LMWH was also observed.Results The pregnancy time involving RSA in LMWH+IUI group significantly increased compared with IUI group([82.67±9.10]d vs [48.17±8.68]d)(P<0.05).The pregnancy success rate and live birth rate in LMWH+ IVF-ET group were both higher than those of IVF-ET group (66.7% vs 35.29%, 85.00% vs 50.00%)(P<0.05) and significant difference was also found in the incidence of RSA, the pregnancy time involving RSA, and the morbidity of gestational hypertension between groups(P<0.05).The results of D2D at 4 weeks of pregnancy in LMWH+IUI group([0.65±0.07]mg/L) and LMWH+ IVF-ET group([0.625±0.06]mg/L) were lower than those of LMWH group ([0.76±0.12]mg/L) and LMWH group([0.77±0.06]mg/L).The result of D2D at 6 weeks of pregnancy in LMWH+IUI group was lower than those of IUI group and IVF-ET group, and D2D in LMWH+ IVF-ET group was lower compared with IVF-ET group(P<0.05).The results of D2D in all the four groups increased with the pregnancy weeks(P<0.05).The prothrombin time(PT) at 4 weeks of pregnancy in LMWH+IUI group, IUI group and LMWH+ IVF-ET group ([12.53±0.38]s, [12.38±0.65]s, [12.47±0.58]s) was significantly higher at pre-pregnancy([12.33±0.52]s, [12.30±0.68]s, [12.22±0.64]s) and 6 weeks of pregnancy([12.13±0.62]s, [12.05±0.60]s, [12.03±0.54]s) (P<0.05).Among 60 cases treated with LMWH, small area ecchymoma were found in 11 cases and the incidence was 18.33%(11/60), only two cases reported with uncomfortable light pain in the location of subcutaneous injection.Conclusion Low-dose LMWH is safe and effective in the therapy of pregnant women with RSA through ART.