Table 1 Definition of low-risk labor^a

Physical findings

Age ≥ 40 years, body weight > 80 kg before pregnancy, primiparas with body-mass index > 25% in antepartum

Complications

Thyroid disease, connective tissue disorder, kidney disease, mental disorder, epilepsy, bronchial asthma, neurological disorder, blood-type incompatible pregnancy, hematologic disease, heart disease, uterine cancer, Rh-type blood-group incompatible pregnancy, high blood pressure, pregnancy-induced hypertension, HIV positive, diabetes, gestational diabetes mellitus, antiphospholipid syndrome, pelvic fracture, placenta previa, pregnancy following conization, non-cephalic presentation after 36 weeks’ gestation, premature birth, multiple pregnancy, intrauterine growth retardation, pregnancy following myomectomy, high-grade cervical dysplasia, abdominal surgery other than cesarean section performed or planned during the pregnancy

Pregnancy course

IVF, pregnancy after extensive fertility treatment, undergoing treatment for sexually transmitted disease, risk of mother-to-child transmission, two or fewer pregnancy check-ups, oligohydramnios, polyhydramnios, placenta previa because of previous cesarean section, received definitive diagnosis of fetal malformation or chromosomal abnormalities

History of gynecological diseases

Large uterine fibroids, post-uterine surgery, cesarean section in previous delivery, placental abruption, underwent or plans to undergo abdominal surgery other than cesarean section, cervical incompetency, two or more spontaneous abortions, congenital disease, history of blood-type incompatible pregnancy, eclampsia/HELLP syndrome, gestational diabetes mellitus, stillbirth, neonatal death, delivery of infant <2500 g, severe gestational hypertension ≥160/110 mmHg, history of delivering infant with major malformations