Risk factors for preterm birth in Korea: a multicenter prospective study.

Preterm birth is a major determinant of neonatal morbidity and mortality and remains one of the most serious problems in obstetrics. The aim of this study was to investigate the risk factors for preterm birth in Korean pregnant women. A total of 2,645 women were evaluated between 20 and 42 weeks' gestation at 5 centers using a prospective study design. The patient population is limited to singleton gestations. Demographic factors, socioeconomic statuses, previous and current medical histories, complications of current gestation, and drug and alcohol abuse were evaluated, and univariate and multivariate logistic regression analyses performed. Among nulliparous women, the factors that showed a significant association with preterm delivery were as follows; vaginal bleeding during pregnancy (OR 2.6, CI 1.7-4.2), and below USD 1,000 average income (OR 5.1, CI 1.9-13.5). The factors that showed a significant association with preterm delivery among multiparous women were as follows; a history of spontaneous abortion (OR 2.4, CI 1.1-5.2), and a history of preterm delivery (OR 3.5, CI 1.02-11.8). In conclusion, vaginal bleeding during pregnancy, below USD 1,000 of average income, prior spontaneous abortion, and prior preterm delivery, were positively associated with preterm birth.