Ms. Labbe said that neither she nor the doctors could answer questions about Mrs. Munoz’s condition because her husband had not signed the paperwork allowing them to speak to the news media about his wife’s care.

At least 31 states have adopted laws restricting the ability of doctors to end life support for terminally ill pregnant women, regardless of the wishes of the patient or the family, according to a 2012 report from the Center for Women Policy Studies in Washington. Texas is among 12 of those states with the most restrictive such laws, which require that life-support measures continue no matter how far along the pregnancy is.

Legal and ethical experts, meanwhile, said they were puzzled by the conflicting accounts of her condition. Brain death, an absence of neurological activity, can be readily determined, they said. It is legally death, even if other bodily functions can be maintained.

“If she is dead, I don’t see how she can be a patient, and I don’t see how we can be talking about treatment options for her,” said Thomas W. Mayo, an expert on health care law and bioethics at the Southern Methodist University law school in Dallas.

Arthur L. Caplan, director of medical ethics at NYU Langone Medical Center in Manhattan, agreed. “The Texas Legislature can’t require doctors to do the impossible and try to treat someone who’s dead,” Mr. Caplan said. “I don’t think they intended this statute the way the hospital is interpreting it.”

Critics of the hospital’s actions also note that the fetus has not reached the point of viability outside the womb and that Ms. Munoz would have a constitutional right to an abortion.

The restrictive measures were largely adopted in the 1980s, with the spread of laws authorizing patients to make advance directives about end-of-life care like living wills and health care proxies, said Katherine A. Taylor, a lawyer and bioethicist at Drexel University in Philadelphia. The provisions to protect fetuses, she said, helped ease the qualms of the Roman Catholic Church and others about such directives.