Background <p>Post-abortion contraception is important for sexual and reproductive health. Combined injectable contraceptives (CICs) are a class of highly effective and reversible contraceptive methods, yet their utilization remains low in China. This study aimed to assess the discontinuation rate, reported side effects, and contraceptive effectiveness of CIC use among post-abortion women in China.</p> Methods <p>We conducted a prospective follow-up study among post-abortion women who received post-abortion care (PAC) services in Shanghai, China, from 2023 to 2024. Post-abortion women who initiated the “Compound Norethisterone Enanthate Injection” (NET-EN 50&#xa0;mg/ E₂V 5&#xa0;mg) were followed up for one year. The chi-square test and survival analysis were used for data analysis.</p> Results <p>A total of 1,156 participants were included. The mean duration of CIC use was 5.73 ± 2.15 months. The one-year discontinuation rate was 98.72% (95% CI: 97.83–99.29). At 6 months, the cumulative user-failure and method-failure rates were 0.49% (95% CI: 0.18–1.30) and 0.12% (95% CI: 0.02–1.13), respectively. Side effects were reported by 331 participants (28.63%), and all had discontinued CIC by the end of follow-up. In univariate analysis, women reporting side effects had a significantly higher discontinuation rate than those without side effects; however, this association was not statistically significant in the multivariable Cox proportional hazards model.</p> Conclusions <p>The one-year discontinuation rate of monthly CIC was high among post-abortion women in this study. The findings highlight the importance of continued contraceptive support and timely access to alternative methods during post-abortion care follow-up.</p>