THE PRETERM PREDICTION STUDY - A CLINICAL RISK ASSESSMENT SYSTEM

OBJECTIVE: Our aims were to develop a risk assessment system for the p rediction of spontaneous preterm delivery using clinical information a vailable at 23 to 24 weeks' gestation and to determine the predictive value of such a system. STUDY DESIGN: A total of 2929 women were evalu ated between 23 and 24 weeks' gestation at 10 centers. Demographic fac tors, socioeconomic status, home and work environment, drug and alcoho l use, and medical history were evaluated. Information regarding sympt oms, cultures, and treatments in the current pregnancy were ascertaine d. Anthropomorphic and cervical examinations were performed. Univariat e analysis and multivariate logistic regression were performed in a ra ndom selection, constituting 85% of the study population. The derived risk assessment system was applied to the remaining 15% of the populat ion to evaluate its validity. RESULTS: A total of 10.4% of women were delivered of preterm infants. The multivariate models for spontaneous preterm delivery were highly associated with spontaneous preterm deliv ery (p < 0.0001). A low body mass index ( < 19.8) and increasing Bisho p scores were significantly associated with spontaneous preterm delive ry in nulliparous and multiparous women. Black race, poor social envir onment, and work during pregnancy were associated with increased risk for nulliparous women. Prior obstetric outcome overshadowed socioecono mic risk factors in multiparous women with a twofold increase in the o dds of spontaneous preterm delivery for each prior spontaneous preterm delivery. Current pregnancy symptoms, including vaginal bleeding, sym ptomatic contractions within 2 weeks, and acute or chronic lung diseas e were variably associated with spontaneous preterm delivery in nullip arous and multiparous women. When the system was applied to the remain der of the population, women defined to be at high risk for spontaneou s preterm delivery ( greater than or equal to 20% risk) carried a 3.8- fold (nulliparous women) and 3.3-fold (multiparous women) higher risk of spontaneous preterm delivery than those predicted to be at low risk . However, the risk assessment system identified a minority of women w ho had spontaneous preterm deliveries. The sensitivities were 24.2% an d 18.2% and positive predictive values were 28.6% and 33.3%, respectiv ely, for nulliparous and multiparous women. CONCLUSIONS: Although it i s possible to develop a graded risk assessment system that includes fa ctors that are highly associated with spontaneous preterm delivery in nulliparous and multiparous women, such a system does not identify mos t women who subsequently have a spontaneous preterm delivery. This sys tem has investigational value as the basis for evaluating new technolo gies designed to identify at-risk subpopulations.