A 24-year-old woman who has been in a coma for the last five years gave birth to a premature baby girl Friday, several months after she was apparently raped while in the care of a Massachusetts nursing home.

Police and state health officials have begun an investigation into the alleged sexual assault, which an informed official said is believed to have occurred about five months ago at a long-term care facility in Lawrence, 30 miles north of Boston. The unidentified woman was taken to Lawrence General Hospital after she went into labor and her legal guardians were notified.

Her child was flown to New England Medical Center in Boston later Friday and remained in critical condition in the neonatal intensive care unit today, according to a hospital spokeswoman.

This is the first recorded case in the state -- and the second in the country -- of a woman in a chronic vegetative state becoming pregnant and giving birth, said Mark Leccese, a spokesman for the Massachusetts Department of Public Health. In 1996, a 29-year-old woman from Rochester, N.Y., who had been in a coma for 10 years gave birth to a baby boy.

"We've never experienced a case like this," Leccese said. "People in nursing homes are the most vulnerable citizens in the state, and it's very important to us to see that they are protected."

A doctor detected the woman's condition Monday after attendants at the Town Manor Nursing and Rehabilitation Center in Lawrence noticed that she appeared to be uncomfortable and suspected she might be pregnant. The woman has been comatose and quadriplegic for five years because of a drug overdose, according to one source familiar with the case.

"This is a highly unusual case, no matter what facility you're dealing with," said Karen Gilliland, spokeswoman for the Sun Healthcare Group in Albuquerque, which has operated the Town Manor nursing home since 1994. "We just want to make sure everything is handled appropriately. The most important thing for us right now is protecting the woman's privacy and her family's privacy."

Gilliland declined to provide further details and there was no information about a suspect.

Essex District Attorney Kevin M. Burke said he is appalled by the situation, which has prompted investigations by local police, prosecutors and health department regulators into possible patient abuse and criminal rape.

"In my 20 years as district attorney, I have never seen anything like this," said Burke in a statement. "We are outraged and will continue to vigorously prosecute this case."

In the New York case, a former nurse's aide in a health care center near Rochester raped and impregnated a patient who had been in a coma for a decade. He was convicted on the basis of DNA tests and imprisoned.

The woman, known only as Kathy, delivered a baby boy who was nine weeks premature and died a few weeks before his first birthday. At the time, doctors said it was unlikely she had any awareness of the rape, pregnancy or birth.

Town Manor is part of a chain of 390 long-term nursing care facilities in 30 states operated by Sun Healthcare Group, which has a number of New England nursing homes that are operated by its SunRise Healthcare subsidiary.

A resident in one of the nursing homes south of Boston was arrested last year for manslaughter after fatally striking a fellow resident in the head. In New Hampshire, a nurse's aide was charged in June with severely abusing patients. And last month, 140 employees at two Massachusetts homes went on strike, demanding higher wages.

The state Department of Public Health has not registered any serious problems at the Lawrence facility, which employs 120 people and has 96 residents. Earlier this year, the nursing home received the highest rating possible in the department's annual survey, which evaluates everything from nurses' services to patient safety during unannounced inspections, Leccese said.