Although Medicaid has increased access to medical care for low-income pregnant women, the Medicaid population remains at high risk for poor pregnancy outcomes. In 1983 the Michigan Department of Public Health conducted 1 week of in-hospital, postpartum interviews addressing risk factors for poor pregnancy outcome among 1,945 women. These births represented over 90% of the births during the study period and constituted a sample of approximately 1.5% of the yearly births in Michigan. Of these women, 24.6% reported receiving Medicaid during pregnancy. The demographic characteristics of the Medicaid women placed them at greater risk for poor pregnancy outcomes than either insured or uninsured women. In terms of medical services, Medicaid recipients began prenatal care later and had fewer visits. In terms of behavioral risks, more Medicaid recipients reported tobacco and alcohol use than did the other mothers. Finally, the infants of Medicaid recipients were 200 g lighter than the other infants. We suggest that the Medicaid program--the major source of prenatal health care for these women--is not adequate to address their risks for poor pregnancy outcomes.