PRETERM DELIVERY AND PERINATAL DEATH AMONG BLACK-AND-WHITE INFANTS INA CHICAGO-AREA PERINATAL REGISTRY

Objective: To explore associations between race, preterm delivery, eti ologic classification of preterm delivery, and perinatal mortality. Me thods: The study population consisted of 13,010 black and 19,007 white mother-infant pairs delivered at Chicago-area hospitals in 1988-1989 categorized as term or preterm births. Preterm births were further div ided by severity and etiology. Black-white differences in perinatal mo rtality within groups were calculated and adjusted for birth weight an d other potential confounding variables. Results: Black women were nea rly twice as likely as whites to experience preterm (before 37 weeks' gestation) and very preterm (before 32, weeks' gestation) delivery ass ociated with premature rupture of membranes (PROM) or classified as id iopathic. Although black infants were also found to have twice the per inatal mortality risk of white infants (relative risk [RR] 2.1, 95% co nfidence interval [CI] 1.7-2.5), the overall preterm perinatal mortali ty rates did not differ between black and white women (RR 1.0, 95% CI 0.8-1.2). However, among preterm births, perinatal mortality was not u niform within categories of medical etiology. The mortality risk was t he same for black and white infants born preterm following polyhydamni os or placental complications (RR 1.1, 95% CI 0.6-1.9), the same for b lack and white infants born preterm after labor induction (RR 1.1, 95% CI 0.6-1.9), and higher for black infants classified as idiopathic pr eterm deliveries (RR 1.6, 95% CI 1.1-2.3). In contrast mortality rates tended to be lower for black infants born preterm following PROM-amni onitis RR 0.8, 95% CI 0.5-1.2). The idiopathic disparity was explained by a differential birth weight distribution (adjusted RR 1.1, 95% CI 0.7-1.9); however, the apparent survival benefit among black infants b orn preterm following FROM increased even further after adjustment for birth weight (adjusted RR 0.4, 95% CI 0.2-0.7). Conclusion: Black inf ants born preterm after PROM appear to have a survival advantage compa red with their white counterparts, an effect not observed within other etiologic categories of preterm delivery.