The hospital maintains that it is following the law, although several experts in medical ethics said they believed the hospital was misinterpreting it. A crucial issue is whether the law applies to pregnant patients who are brain-dead as opposed to those in a coma or a vegetative state. The law, first passed by the Texas Legislature in 1989 and amended in 1999, states that a person may not withdraw or withhold “life-sustaining treatment” from a pregnant patient.

Mr. and Mrs. Machado said the hospital had made it clear to them that their daughter was brain-dead, but hospital officials have declined to comment on Mrs. Munoz’s care and condition, creating uncertainty over whether the hospital has formally declared her brain-dead.

A spokeswoman for the J.P.S. Health Network, the publicly financed hospital district in Tarrant County that runs the 537-bed John Peter Smith Hospital, defended the hospital’s actions. “In all cases, J.P.S. will follow the law as it applies to health care in the state of Texas,” the spokeswoman, Jill Labbe, said. “Every day, we have patients and families who must make difficult decisions. Our position remains the same. We follow the law.”

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.