Objective To investigate the effects of different doses of aspirin combined with dydrogesterone on the immune microenvronment, the success rate of fetal preservation, and adverse reactions in patients with anticardiolipin antibody-positive threatened abortion.

Methods This was a prospective randomized controlled trial. A total of 90 patients with immune-factor-related threatened abortion from January 2021 to December 2024 were enrolled as the study subjects. They were randomly divided into control group (dydrogesterone), low-dose group (aspirin 50 mg combined with dydrogesterone), and high-dose group (aspirin 100 mg combined with dydrogesterone) using stratified block randomization, with 30 cases in each group. The levels of type 1/type 2 helper T cell cytokines (Th1/Th2), the success rate of fetal preservation, and adverse reactions were compared among the three groups before and after treatment.

Results After treatment, the levels of TNF-α and IFN-γ in all three groups were lower than those before treatment. The levels of these indicators in the low-dose and high-dose groups were lower than those in the control group, with statistically significant differences (P < 0.05). After treatment, the levels of IL-4 and IL-10 in all three groups were higher than those before treatment, the levels of IL-4 and IL-10 in the low-dose and high-dose groups were higher than those in the control group, with statistically significant differences (P < 0.05). The success rates of fetal preservation in the low-dose and high-dose groups were 86.67%(26/30) and 93.33%(28/30), respectively, which were both higher than that in the control group (63.33%, 19/30), with statistically significant differences (P < 0.05). The incidence of adverse reactions was 16.67%(5/30) in the control group, 20.00%(6/30) in the low-dose group, and 46.67%(14/30) in the high-dose group. The incidence of adverse reactions in the high-dose group was higher than that in the low-dose and control groups, with statistically significant differences (P < 0.05).

Conclusion Low-dose aspirin combined with dydrogesterone has significant effects in improving the immune microenvironment and increasing the success rate of fetal preservation in patients with anticardiolipin antibody-positive threatened abortion, with a low incidence of adverse reactions.