Objective To explore the predictive value of serum thrombospondin-1 (TSP-1) and soluble B7-H3 (sB7-H3) levels in early pregnancy for adverse pregnancy outcomes in patients with recurrent spontaneous abortion (RSA). Methods A total of 92 patients with RSA admitted to Shangqiu Municipal Hospital from February 2023 to February 2024 were selected as the study group, and 50 normal pregnant women during the same period were selected as the control group. The levels of TSP-1 and sB7-H3 in the early pregnancy serum of the two groups were detected by enzyme-linked immunosorbent assay (ELISA). Follow- up was conducted until the end of pregnancy in the study group. Subjects were divided into a subgroup with adverse outcomes and a subgroup with favorable outcomes according to different clinical outcomes. Differences in indicators were compared, and correlation analysis, logistic regression, and receiver operator characteristic (ROC) curves were used to evaluate the relationship and predictive value. Results The study group had lower TSP-1 and higher sB7-H3 levels than the control group (both P＜0.001). In the study group, 31 cases (33.70%) experienced adverse pregnancy outcomes. The level of TSP -1 in the adverse outcome subgroup was lower than that in the favorable outcome subgroup, while the level of sB7-H3 was higher in the adverse outcome subgroup than in the favorable outcome subgroup (both P＜0.001). TSP-1 was negatively correlated with adverse outcomes (r＝-0.426), while sB7-H3 was positively correlated (r＝0.489) (both P＜0.001). Multivariate Logistic regression analysis showed that both low levels of TSP-1 and high levels of sB7-H3 were independent risk factors for adverse outcomes (both P＜0.05). The ROC curve revealed that the area under the curve (AUC) of the combined detection achieved 0.971, with a sensitivity of 90.32 and a specificity of 98.36. The predictive efficacy of the combined detection was superior to that of single indicators. Conclusion RSA patients exhibit decreased serum TSP-1 and increased sB7-H3 levels in early pregnancy, both of which are independent risk factors for adverse pregnancy outcomes. Combined detection shows high predictive value for adverse outcomes and may serve as a potential serological marker for early pregnancy prognosis assessment.