A Catholic hospital system operating 15 hospitals and another 132 facilities in Illinois and Michigan has adopted a policy to only cover fertility treatment for workers in opposite-sex marriages.

Illinois-based OSF HealthCare, which has more than 24,000 health care workers, changed the language of its fertility treatment policy to explicitly refer to opposite sex-couples only, according to documents reviewed by Bloomberg Law, meaning employees who are in a same-sex marriage would not be covered.

The policy could be illegal under federal laws prohibiting the discrimination against someone for their sexual orientation.

It would also would likely run afoul of the 2020 U.S. Supreme Court case Bostock v. Clayton County, which ruled an employer cannot discriminate against an individual based on their sexual orientation because it would violate Title VII in the 1964 Civil Rights Act.

OSF Healthcare is owned by the Sisters of the Third Order of St. Francis, a Roman Catholic organization in Peoira, Ill.

Discrimination against same-sex couples and LGBTQ members who seek to raise a child is part of multiple ongoing civil rights battles in the U.S.

Last year, health insurance company Aetna was sued in a class-action lawsuit alleging it forces same-sex couples to pay more out-of-pocket fees than opposite-sex couples.

Under the Biden administration, the federal government has taken steps to prohibit discrimination against the LGBTQ community, including an executive order last month that expands protections for the community through federal programs.

In August, the U.S. Citizenship and Immigration Services updated its policies to include children born through assisted reproductive technology to be considered born in wedlock, a huge step for same-sex married couples who use in vitro fertilization or surrogacy to have a child.