Medicaid Infant Mortality Amendments of 1991 - Amends title XIX (Medicaid) of the Social Security Act to phase-in mandatory State coverage of pregnant women and infants whose family income is below 185 percent of the Federal poverty level. Deducts child and medical care costs from the income eligibility test.

Authorizes States to provide Medicaid coverage of prenatal home visitation services for high-risk pregnant women and/or postpartum home visitation services for high-risk infants.