preterm births occur among non-Hispanic blacks and the lowest percentages occur among Asians and Pacific Islanders, the most notable increases in the percentages of preterm births from 2001 to 2003 were for the white non-Hispanic, American Indian, and Hispanic groups. Overall, the rise in the proportion of preterm births in the United States was due mostly to the increase among the non-Hispanic white population.
The proportion of preterm births among white non-Hispanic women increased from 8.5 percent in 1990 to 11.3 percent in 2003. The proportion has remained fairly stable among Asian and Pacific Islander women (at about 10 percent). Among black women, although the proportion decreased from 18.9 percent in 1990 to 17.8 percent in 2003, overall, these women continue to experience much higher proportions of preterm births.
Although the proportion of preterm births among Hispanic and Asian-Pacific Islander women are the lowest of those among the ethnic and racial minority groups, these are not homogeneous populations. Considerable variation in preterm birth percentages exists among subpopulations of these populations. Although the percentage of preterm births for Hispanics in the United States was 11.9 in 2003, the percentages within subgroups of the Hispanic population ranged from 11.4 to 13.8 percent (Figure 1-9). Compared with other Hispanic subgroups, Puerto Rican women had the highest percentages and Central and South American women had the lowest.
In 2002, the Asian and Pacific Islander subgroups of American women had preterm birth percentages that ranged from 8.3 to 12.2 (Figure 1-10). The Hawaiian (11.7 percent) and Filipino (12.2 percent) subgroups of