The Comparison of the Rate of Complete Abortion between Letrozole Plus Misoprostol versus Misoprostol Alone in First-Trimester Spontaneous Pregnancy Loss: A Randomized Controlled Trials

Background: Prior studies have indicated that using letrozole together with misoprostol is more effective than misoprostol alone for medical termination. At present, there are no studies about letrozole for termination of pregnancy in the Thai population. Objective: To compare the rate of complete abortion between the regimen of letrozole followed by misoprostol and misoprostol alone in women diagnosed with early pregnancy loss at a gestational age of 14 weeks or less, and to evaluate the adverse effects of both regimens. Materials and Methods: A clinical randomized control trial was conducted with 70 women diagnosed with early pregnancy loss. The intervention group, with 35 patients, received 10 mg of letrozole daily for three days followed by three doses of 800 mcg sublingual misoprostol. The control group, with 35 patients, received sublingual misoprostol alone. The primary outcome was to compare the rate of complete abortion between letrozole administered three days prior to misoprostol versus misoprostol alone. The secondary outcomes were to evaluate the adverse effects of both regimens. Results: There were no significant differences in demographic data between the two groups, including age, underlying disease, body weight, height, body mass index and gestational age. In the intervention group, complete abortion occurred in 65.7% of cases compared to 62.9% in the control group. This showed no significant differences between the two groups (p-value of 0.803). Additionally, there were no significant differences in clinical adverse effects, including nausea and vomiting, diarrhea, dizziness, headache, abdominal pain, fever, and chills. Conclusion: The combination of letrozole and misoprostol does not enhance the rate of complete abortion for termination of first trimester pregnancy. In addition, the adverse effects are not significantly decreased.