State policies differ dramatically on what to do if pregnant women are dying and are too incapacitated to express their wishes, Mayo Clinic researchers found.

Twenty-five states would invalidate advance directives and continue life support in incapacitated pregnant women, in some cases regardless of whether their babies are likely to be saved, the researchers found. Nineteen states also would restrict surrogate decisionmakers in these scenarios.

While the variation was surprising, the researchers said they were concerned about the lack of transparency. Out of 30 states that would restrict decisionmaking, only 11 required disclosure of such restrictions on advanced directive forms.

“To not have that disclosed, that when you are pregnant the form you are signing carries no force … is really troubling,” said Dr. Erin DeMartino, the Mayo critical care specialist who led the study along with a national group of bioethicists.

Minnesota is one of eight states that prompts women on advance directive forms to indicate what to do in pregnancy situations. However, DeMartino said the state is not transparent about the fact that it will prevent withdrawal of life support in women during childbirth who have not clearly expressed those wishes.

That underlying legal presumption is important, she said, because advance directives are usually completed by the old and the sick — not women in childbearing years.

The results, published in the Journal of the American Medical Association, are believed to be the first roundup of state policies on this issue.

Some state policies used terms such as “unborn child” that suggested they were influenced by the abortion debate, but DeMartino said some states had policies that somewhat contradicted their prevailing political and abortion views.

Actual cases are rare. A Texas hospital kept a 33-year-old woman alive for two months in 2014 because she was 14 weeks pregnant at the time she suffered brain death from a pulmonary embolism. A court order eventually agreed with the family’s request to withdraw life support before her fetus was developed enough to attempt a surgical delivery.

DeMartino said it is important to examine these policies even if incidents are rare.

“It raises a lot of important questions around how we as a society view fetuses and fetal interests,” she said, “and how we balance that against the autonomy of half of our adult population — women.”