Pregnancy outcomes improved significantly over the 20th century in the United States but currently vary widely between women of different ethnic and racial backgrounds. The current health disparities that exist are based, in part, only on differences in socioeconomic status or education. There is wide variability in pregnancy outcomes within specific subgroups of women. Disparities may be due to underlying differences in health before pregnancy, differences in community norms, and individual lifestyle choices and to differences in health care delivery systems. Areas for needed research and promising new models of care are reviewed.