A Michigan woman has been denied a potentially life-saving medical procedure on religious grounds by her Catholic hospital, weeks before she gives birth.

Jessica Mann was told that she could not have her fallopian tubes tied during her scheduled caesarean section, despite her doctor advising it.

She has a life threatening brain tumour and her doctor advised that she should have a tubal ligation to avoid further pregnancies, which could exacerbate her tumour.

Catholic mandates do not allow procedures that cause sterilisation and so the hospital has refused to do the procedure.

A formal complaint has been filed against the hospital.

Mann, who is 37 weeks' pregnant, was forced to find a new hospital to be treated in, a week before her due date.

"I am very close to giving birth and instead of being excited, I'm terrified because my hospital turned me away, and I've had to go find a new doctor and hospital with little time to get them up speed on my complicated medical history and health risks," she said.

"All of this could have been avoided if Catholic bishops weren't allowed to play doctor at hospitals that serve the public."

The hospital, Genesys Hospital, is part of Ascension Health, in which "Ethical and Religious directives" written by Bishops govern the facility.

It was according to a religious directive that Mann was refused treatment.

The American Civil Liberties Union of Michigan, who have filed a formal complaint, have said: "We're taking the fight to the state agency that governs the hospital because it's their job to make sure women like Jessica get the care they need.

"Religious directives have no place in hospitals, especially because they end up harming the very women they should be serving."

According to ACLU, 10 of the 25 largest hospital systems in the US are Catholic-sponsored and one in nine hospital beds in the country is in a Catholic hospital.