State-specific changes in singleton preterm births among black and white women--United States, 1990 and 1997.

National infant mortality rates among non-Hispanic black women are twice those of non-Hispanic white women (1). Nearly two-thirds of this disparity is attributable to a higher rate of preterm delivery (PTD) (i.e., < or = 37 weeks' gestation) among blacks (2). To investigate state-specific changes in PTD rates among blacks and whites, natality data for 1990 and 1997 were analyzed from 50 states and the District of Columbia (DC). These data indicated that, although the PTD rate was twice as high among blacks than among whites, the disparity decreased as the result of an increase in preterm births among whites and a decrease among blacks (3).