Strengths and Limitations
This is the first interventional study to investigate the prevention of preterm birth in pregnant women after AT and describe the obstetric and antepartum complications in detail. One limitation of our study was the absence of randomization. However, the study groups were separated by a time period, and clinicians could not use their discretion to determine whether vaginal progesterone should be administered. Therefore, we believe that the backgrounds in both groups were similar and that our study has a certain level of precision as a comparison analysis. Another limitation was the small sample size. Initially, we had planned to accumulate data from a larger sample size for a longer study period; however, based on the apparently ineffective results presented herein, the only alternative was to stop this interventional study early, considering that any study in a clinical setting should be performed on behalf of patients.