Healthy Maternity and Obstetric Medicine Act or the Healthy MOM Act This bill amends the Public Health Service Act and Internal Revenue Code to require health insurers, health insurance exchanges, and group health plans to offer a special enrollment period to pregnant individuals. The special enrollment period offered by an insurer or exchange must begin when the pregnancy is reported to the insurer or exchange. The special enrollment period offered by a group health plan must begin when the pregnancy is reported to the plan or is confirmed by a health care provider. Coverage offered by a group health plan or health insurer that covers dependents must provide coverage for maternity care to all covered individuals. The Office of Personnel Management must ensure that eligible pregnant women are allowed to enroll in federal employee health benefit plans outside of the open enrollment period. This bill amends title XIX (Medicaid) of the Social Security Act to revise the range in which a state must establish a maximum level of family income for pregnant women and infants to be eligible for Medicaid. The upper limit of the range is eliminated and the lower limit is set to the level in place, or specified in an amendment to a state plan, on January 1, 2014.