Results
From 2014 to 2015, 789,482 women delivered in Korea. After excluding women with missing data (n = 515), 788,967 remaining women were included in dataset 1. Among them, 740,675 (93.88%) women had no diagnosed myoma, 38,402 (4.88%) had diagnosed myoma(s) but no history of myomectomy, and 9,890 (1.25%) women had a history of myomectomy before pregnancy. Dataset 2 included 534,259 women, excluding women whose infants did not receive infant screening (n = 254,693) or showed missing values (n = 15). There were 502,209 (94.00%) women who had never been diagnosed with myoma, 25,408 (4.76%) women who had diagnosed myoma(s) but no history of myomectomy, and 6,642 (1.24%) women who had a history of myomectomy, in dataset 2.
Maternal characteristics and adverse pregnancy outcomes of the study population in dataset 1 as described in Table 1. There were significant differences in maternal age, rates of nulliparity, multiple pregnancy, cesarean section, and complications of preeclampsia, postpartum hemorrhage, placenta previa, and uterine rupture, between the groups. However, there was no significant difference in placental abruption between the three groups.
Obstetric characteristics in dataset 2 are presented in Table 2. There were significant differences in neonatal birth weight and sex, and rates of preterm birth, LBW, and LGA.