To determine whether lack of financial access was a significant barrier to prenatal care following major expansions of Medicaid eligibility in California. Retrospective analysis of birth certificates, assessing risks of inadequate prenatal care by insurance, controlling for maternal race/ethnicity, birthplace, age, parity, education, and marital status. Singleton live births to California residents occurring in-state in 1990 (N = 593,510). Untimely initiation of care, two few visits, and no prenatal care. Despite major Medicaid expansions, nearly 11% of live births were uninsured for prenatal care. Being uninsured and having Medi-Cal were both risk factors of sizable magnitude, controlling for maternal characteristics. Compared with women who had private fee-for-service coverage, uninsured women were at elevated risk of untimely initiation (odds ratio [OR], 2.54; 95% confidence interval [CI], 2.47 to 2.60) and too few visits (OR, 2.49; 95% CI, 2.44 to 2.55). Women with Medi-Cal had a high risk of untimely care (OR, 3.33; 95% CI, 3.26 to 3.40); their risk of too few visits was also elevated (OR, 1.63; 95% CI, 1.60 to 1.66) but less than for the uninsured. Lack of private insurance was a strong risk factor for no care (OR, 6.70; 95% CI, 6.00 to 7.47). In spite of major Medicaid expansions, access to prenatal care was limited for women without private insurance. Medicaid was associated with untimely entry but with improved continuity. The findings suggest that financial barriers were salient even when controlling for many factors related to care-seeking behavior. Policy initiatives need to address continuing financial barriers along with other obstacles.