Minor Child and medical bills

We have received medical bills for my husband's daughter. She is 17 and had a miscarriage when she was 16, that was treated without our knowledge or consent. Our insurance has refused payment as maternity services are uninsured for dependents under our plan. My husband has legal custody of this daughter. She was in our custody in Utah at the time of the miscarriage but now lives with her mother in Michegan. Are we legally liable for these bills or can we insist that she takes responsibility for the consequences of her actions? How do we prevent being liable for medical costs for a possible future viable pregnancy and birth?
Many thanks