THE PRETERM PREDICTION STUDY - RISK-FACTORS FOR INDICATED PRETERM BIRTHS

OBJECTIVE: Preterm births occur for many different reasons. R/lost eff orts to identify risk factors for preterm births either ignore cause a nd consider preterm births as a single entity or examine risk factors for spontaneous preterm births. We performed this study to examine ris k factors for indicated preterm births, which constitute more than one quarter of all preterm births. STUDY DESIGN: The study included 2929 women evaluated at 24 weeks' gestation at 10 centers. Information was gathered about demographic factors, socioeconomic status, home and wor k environments, drug and alcohol use, and medical history In addition vaginal samples were evaluated for fetal fibronectin and bacterial vag inosis and cervical length was measured by transvaginal ultrasonograph y. Associations with indicated preterm birth were evaluated by univari ate tests and by multivariable analysis with logistic regression. RESU LTS: Of the women studied at 24 weeks' gestation 15.3% were delivered of their infants at <37 weeks' gestation. Of these deliveries, 27.7% w ere indicated preterm births. Risk factors in the final multivariable model were, in order of decreasing odds ratios, mullerian duct abnorma lity (odds ratio 7.02), proteinuria at <24 weeks' gestation (odds rati o 5.85), history of chronic hypertension (odds ratio 4.06), history of previous indicated preterm birth (odds ratio 2.79), history of lung d isease (odds ratio 2.52), previous spontaneous preterm birth (odds rat io 2.45), age >30 yeats (odds ratio 2.42), black ethnicity (odds ratio 1.56), and working during pregnancy (odds ratio 1.49). Alcohol use in pregnancy was actually associated with a lower risk of indicated pret erm birth (odds ratio 0.35). CONCLUSION: The risk factors found in thi s analysis tend to be different from those associated with spontaneous preterm birth.