Strong Families Act of 2017 This bill amends title V (Maternal and Child Health Services) of the Social Security Act to reauthorize through FY2022, and otherwise revise, the Maternal, Infant, and Early Childhood Home Visiting Program. Under current law, grantees were required, after three years of program implementation, to demonstrate improvement in specified benchmark areas. The bill requires grantees to continue to track and demonstrate, on a triennial basis, improvement in applicable benchmark areas. A grantee that fails to do so must develop and implement a corrective action plan, subject to approval by the Department of Health and Human Services (HHS). HHS shall terminate a program grant made to a grantee that implements such a plan but continues to fail to demonstrate improvement. As a condition for receiving grant funds under the program, a state must review and update its statewide needs assessment by October 1, 2020. A grantee may use a portion of program grant funds to support a "pay-for-outcomes initiative" (a performance-based grant, contract, or cooperative agreement, awarded by a public entity, in which a commitment is made to pay for improved outcomes that result in social benefit and public-sector cost savings). HHS must designate data-exchange standards applicable to the program.