Illinois law requires insurance companies to provide coverage for diagnostic tests and treatment to those receiving insurance from an employer with more than 25 employees. As of January 1, 2022, the law is applicable for same-sex couples, women over 35, single persons, and those who cannot get pregnant naturally due to a medical reason.
However, there are exceptions. The law does not apply to individual policies, small group policies (fewer than 25 employees) or insurance policies outside of Illinois (i.e., it may not be covered if you live in Illinois but have insurance through an employer in another state).