Medicaid Infant Mortality Amendments of 1991 - Amends title XIX (Medicaid) of the Social Security Act to require mandatory State coverage of pregnant women and infants whose family income is below 185 percent of the Federal poverty level. Provides 100 percent Federal financing of the costs of services to pregnant women and infants whose family income is between 133 and 185 percent of the Federal poverty level. Prohibits application of resource testing to pregnant women and infants.

Authorizes States to provide Medicaid coverage of home visitation services with respect to high-risk infants.

Provides for flexibility in determining the limitation on Federal payments to States for Medicaid services provided to pregnant women and infants.

Requires States to include in their Medicaid benefit packages primary health services for residents of public housing provided by an entity which meets the requirements to receive a grant under the Public Health Service Act to fund the provision of such services.