Nationwide population-based cohort study of adverse obstetric outcomes in pregnancies with myoma or following myomectomy: retrospective cohort study.

Background: Our objective was to evaluate risks of adverse obstetric outcomes in pregnancies with myoma(s) or in pregnancies following myomectomy.
Methods: We analyzed the national health insurance database, which covers almost the entire Korean population, between 2004 and 2015. The risks of adverse pregnancy outcomes in pregnancies with myoma(s) or in pregnancies following myomectomy, compared to those in women without a diagnosed myoma, were analyzed in multivariate logistic regression analysis.
Results: During the study period, 38,402 women with diagnosed myoma(s), 9890 women with a history of myomectomy, and 740,675 women without a diagnosed myoma gave birth. Women with a history of diagnosed myoma(s) and women with a history of myomectomy had significantly higher risks of cesarean section (aOR 1.13, 95% CI 1.1-1.16 and aOR 7.46, 95% CI 6.97-7.98, respectively) and placenta previa (aOR 1.41, 95% CI 1.29-1.54 and aOR 1.58, 95% CI 1.35-1.83, respectively), compared to women without a diagnosed myoma. And the risk of uterine rupture was significantly higher in women with previous myomectomy (aOR 12.78, 95% CI 6.5-25.13), compared to women without a diagnosed myoma, which was much increased (aOR 41.35, 95% CI 16.18-105.69) in nulliparous women. The incidence of uterine rupture was the highest at delivery within one year after myomectomy and decreased over time after myomectomy.
Conclusions: Women with a history of myomectomy had significantly higher risks of cesarean section and placenta previa compared to women without a diagnosed myoma.