Strengths and Limitations
The major strengths of our study are the large sample size and the use of PSM methods to eliminate the potential impacts of maternal age and parity, prior history of abortion, mode of conception and pre-pregnancy BMI. Furthermore, this study first explored the impacts of the number of HA surgeries and the time interval from complete surgery to the date of conception on obstetric outcomes. However, there are some limitations that warrant attention. First, all participants of our study were from one of the largest cities in China, which may limit the generalizability of our findings. Second, due to lack of sufficient untreated pregnancies with IUAs, we could not determine whether the increased risk of adverse obstetric outcomes was attributed to the HA treatment or the disease of IUAs itself. Finally, all data were from medical records, and due to data inaccessibility, we could not obtain the AFS score of each IUA case. However, we used the number of hysteroscopic surgeries a woman underwent to reflect the severity of their IUAs. Scoring of IUA and adjuvant treatment after HA are crucial factors of prognosis and more prospective research are need to be further investigated whether these factors have impact on obstetrical outcomes.