To evaluate the effect of low molecular weight heparin (LMWH) for treating women with recurrent spontaneous abortion (RSA), and to study the changes of Th1/Th2 cytokines levels in peripheral blood and uterine artery blood flow resistance of these patients. Methods: A total of 109 women with RSA were selected and were divided into group A (61 women with treatment of dalteparin sodium combined with progesterone) and group B (48 women with treatment of aspirin combined with progesterone) according to different treatment methods from April 2019 to June 2021. 50 normal pregnant who had been pre-pregnancy examinees were included in group C during the same period. The values of peak endsystolic/end-diastolic velocity (S/D), pulsatility index (PI), resistance index (RI), and the levels of Th1/Th2 cytokines, such as interleukin-2 (IL-2), interferon gamma (IFN-γ), tumor necrosis factor (TNF-α), IL-4, and IL-10 of the women in the three groups were detected. The pregnant situation and the adverse reactions rate of the women during 30 gestational weeks in the three groups were observed. Results: Before treatment, the values of arterial blood flow resistance S/D, PI, and RI of the women in group A and group B were significantly higher than those of the women in group C. After treatment, the values of S/D, PI, and RI of the women in group B and group A had decreased significantly, and which of the women in group A was significantly lower than that of the women in group B (P＜0.05). Before treatment, the levels of IL-2, IFN-γ, and TNF-α of the women in group B and group A were significantly higher than those of the women in group C, while the levels of IL-4 and IL-10 of the women in group B and group A were significantly lower than those of the women in group C (P＜0.05). The levels of IL-2, IFN-γ, and TNF-α of the women in group A and in group B after treatment had decreased significantly, and the levels of IL-4 and IL-10 of the women in group A and in group B after treatment had increased significantly, and both of which of the women in group A were significantly higher than those of the women in group B (P＜0.05). In 30 gestational weeks, the prevent miscarriages rate of the women in group C was 100.0% (50 cases), that of the women in group B was 79.2% (38 cases), and that of the women in group A was 93.4% (57 cases), and which of the women in group A was significantly higher than that of the women in group B (P=0.001). There was no significant difference in the total adverse reactions rate (22.9% vs. 25.0%) of the women between group A and group B (P＜0.05). Conclusion: The LMWH combined with progesterone for treating women with RSA can better reduce their uterine artery blood flow resistance, maintain their Th1/Th2 immune balance and their pregnancy, and improve their clinical efficacy, with better safety.