A Flint-area Catholic hospital violated a provision of the Affordable Care Act (ACA) when it refused to perform a postpartum tubal ligation on a brain tumor patient last year, the American Civil Liberties Union (ACLU) and its Michigan affiliate alleged in a complaint filed Tuesday.

The complaint targets Ascension Health, which claims to be the largest Catholic health system in the world and the largest nonprofit health system in the United States.

The health system owns the Genesys Regional Medical Center in Grand Blanc, Michigan, which refused to perform the procedure on patient Jessica Mann last September. Genesys cited the Ethical and Religious Directives authored and enforced by the U.S. Conference of Catholic Bishops (USCCB) in refusing the procedure, according to the ACLU.

The ACLU said the hospital’s decision left Mann scrambling for a new doctor less than two months before her scheduled cesarean section. Mann had delivered her first two children and had a previous brain tumor removed at the same hospital.

“At a time when I should have been focused on getting ready to bring my baby into the world, I instead had to frantically search for a new doctor and a new hospital to get the care I needed to protect my life, because the local hospital where I had been a patient for fifteen years forbid it,” Mann said in a statement. “I don’t want other women to be turned away from hospitals that let their religious views trump their patients’ serious medical needs.”

The ACLU, in its complaint to the Office for Civil Rights under the U.S. Department of Health and Human Services (HHS), said the act violated the nondiscrimination provision of the ACA.

Section 1557, as the provision is known, prohibits discrimination on the basis of race, color, national origin, sex, age, or disability in certain health programs.

The ACLU said the hospital system’s ban on postpartum tubal ligations violated Section 1557 because the policy discriminates on the basis of sex by “denying women a fundamental component of pregnancy- and childbirth-related care.” The advocacy group said the hospital system violated the provision by “denying women, but not men, the medical standard of care, and subjecting women to a heightened risk of unintended pregnancy.”

Mann, who had a pre-existing tumor, had been advised by maternal-fetal medicine specialist Dr. Ivana Vettraino to have a tubal ligation at the time of her scheduled c-section. Vettraino advised that, due to Mann’s brain tumor, another pregnancy would be life-threatening, according to the ACLU.

The American Congress of Obstetricians and Gynecologists considers the postpartum tubal ligation process to be a quick, low-risk procedure.

Vettraino, in a formal exception request made to the hospital, explained that anesthesia was a risk for Mann.

“To undergo a separate procedure requiring an additional episode of anesthesia when the tubal ligation can be performed with the anesthesia required for the cesarean delivery does not appear to make any sense in regard to patient safety,” Vettraino said.

The ACLU said Genesys waited more than three months to inform Mann’s doctor that the special request had been denied.

Dan Korobkin, deputy legal director at the ACLU of Michigan, noted in a recent statement that nearly one in four hospital beds in Michigan is owned by a Catholic hospital.

The ACLU said it had received complaints from other residents affected by Genesys’ tubal ligations ban and had sent a letter more than a year ago to the Michigan Department of Licensing and Regulatory Affairs, requesting an investigation “into the ban’s serious implications for women’s health.” No investigation was initiated.

In collaboration with MergerWatch, the ACLU highlighted the prevalence of Catholic hospitals and its effect on people seeking reproductive care in a report titled, “Health Care Denied.”

The report, released in May, found that one in six hospital beds in the United States is in a facility that complies with Catholic health directives.

In April, a month before the report was released, the 41,000-member California Medical Association (CMA) joined the ACLU in suing Dignity Health, a Catholic health system, for banning doctors from performing postpartum tubal ligations.

Dignity Health is California’s largest hospital system and recently made headlines for refusing on religious grounds to perform a hysterectomy on a transgender man.