Risk Factors for Failure of Second-Trimester Termination with Misoprostol as a Single Agent

Background: Understanding the potential risk factors for failure of pregnancy termination is crucial for informed clinical decision making. Such insights can assist clinicians in adjusting the dosage or route of various regimens, as well as in counseling patients and predicting the likelihood of successful outcomes. However, research on these risk factors has been limited, and existing studies have yielded inconsistent results. To address this gap, we conducted a study with a large sample size, focusing on identifying the potential risk factors for failure of second-trimester termination using misoprostol as a single agent, specifically between 14 and 28 weeks of gestation. Methods: A secondary analysis based on a database of second-trimester terminations was conducted. The inclusion criteria were a singleton pregnancy, gestational age between 14 and 28 weeks, an unfavorable cervix, no spontaneous labor pain, intact membranes, and termination with misoprostol alone. Potential risk factors for failure of termination, defined as no abortion within 48 h, were analyzed using univariate and multivariate analyses. Results: A total of 1094 cases were included in the analysis, consisting of 991 successful cases and 103 (9.4%) cases of failure. The significant risk factors for failure of termination included early gestational age, live fetuses, sublingual regimen of 400 mcg every 6 h, and high maternal pre-pregnancy BMI. Previous cesarean sections and lower Bishop scores tended to increase the risk but did not reach a significant level. Conclusions: Second-trimester termination with misoprostol as a single agent was highly effective, with a failure rate of 9.4%. The risk factors for failure included gestational age, fetal viability, misoprostol regimen, and maternal pre-pregnancy BMI, suggesting that these factors should be taken into consideration for second-trimester terminations with misoprostol.