Associations between the time interval from myomectomy to subsequent pregnancy and the obstetric outcomes: A population-based cohort study

OBJECTIVE: To investigate the associations between time interval from myomectomy to pregnancy (TIMP) and subsequent pregnancy and obstetric complications, and to explore whether these associations vary according to maternal age at birth.

METHODS: A retrospective population-based cohort study was conducted from 2008 to 2017. Data were extracted from the National Health Insurance Research Database and the Taiwan Maternal and Child Health Database, comprising 2024 379 births from 1 391 856 pregnancies. Eligible cases were identified using diagnostic and procedure codes; 4006 first singleton births in 4006 women after their first laparotomic myomectomy were identified. We estimated the risks of pregnancy and obstetric outcomes according to TIMP (<6, 6-11, and ≥12 months). Subgroup analysis was performed by further dividing according to maternal age at birth (18-34 vs ≥35 years old).

RESULTS: We observed higher risks of gestational hypertensive disorders (adjusted odds ratio [aOR] 1.97, 95% confidence interval [CI] 1.22-3.18, P = 0.005) and neonatal death (aOR 4.59, 95% CI 1.49-14.18, P = 0.008) for TIMP of <6 months versus TIMP of 6-11 months. Likewise, a TIMP ≥12 months was associated with increased risks of gestational hypertensive disorders (aOR 1.72, 95% CI 1.14-2.58, P = 0.010), and neonatal death (aOR 3.27, 95% CI 1.16-9.24, P = 0.025) versus a TIMP of 6-11 months. In subgroup analysis, women over 35 years old still had higher risks of gestational hypertensive disorders when TIMP was <6 months (aOR 2.26, 95% CI 1.17-4.37, P = 0.015) or ≥12 months (aOR 2.04, 95% CI 1.17-3.54, P = 0.012), and a higher risk of neonatal death when TIMP was <6 months (aOR 4.05, 95% CI 1.06-15.53, P = 0.041); whereas women aged 18-34 years old did not.

CONCLUSIONS: This study suggests that a TIMP between 6 and 11 months is associated with lower risks of gestational hypertensive disorders and neonatal death compared with a TIMP <6 months or ≥12 months, especially for women over 35 years old.