Outcomes
Using the KNHI claims database, we identified all women who had given
birth between January 1, 2014, and December 31, 2015. We also identified
whether these women had a diagnosis of uterine myoma based on ICD-10
codes before pregnancy and whether these women had a myomectomy using
procedure codes from the Health Insurance Medical Care Expenses.
The flow chart of study participants’ enrollment is presented in Figure
1. For pregnancy outcomes, we extracted information on delivery mode,
nulliparity, multiple pregnancy, preeclampsia, PPH, placental abruption,
placenta previa, and uterine rupture using the KNHI claims database
(dataset 1). For the other outcomes, the KNHI claims database and the
NHSP-IC database were merged. Because data on preterm birth and birth
weight were corrected from the NHSP-IC database, women were excluded
from analysis if their offspring did not undergo at least one of the
seven consecutive NHSP-IC examinations or had missing data (dataset 2).
Data on preterm birth, low birth weight (LBW), and large for gestational
age (LGA) were extracted from dataset 2. Preterm birth was defined as
gestational age < 37 weeks. LBW was defined as birth weight
< 2.5 kg. LGA was defined as birth weight >
4.0 kg.