Baby Fae, the longest-surviving human recipient of an animal heart, may have suffered permanent damage from her body's first effort to reject the alien tissue and will likely have several more such crises, doctors said today.

But officials at the Loma Linda University Medical Center said the infant, 1 month old today, was recovering well from a slack beat in her transplanted baboon heart and a dangerous increase in her body's infection-fighters that marked her first rejection episode.

"We are encouraged and hopeful that she will come out of this triumphant," said Dr. David B. Hinshaw, a surgeon at this Seventh-day Adventist institution and a spokesman for the baby's doctors.

The hospital's morning medical report said signs of dangerous infection-fighting substances in Baby Fae's blood had declined in the last 24 hours. Although she still was not producing enough urine, a sign of reduced heart and kidney function, "she remains pink and warm, without fever," the report said.

At a crowded news conference at this university 60 miles east of Los Angeles, Hinshaw decried an NBC News report that he said "called into question the basic ethics" of the hospital's doctors.

NBC reported Tuesday night that Baby Fae's parents, who have asked hospital officials to keep their names confidential, had little money when their baby was born Oct. 14 with hypoplastic left heart syndrome, a severe deformity that usually is fatal within weeks if untreated. The network also said the mother had been charged with passing bad checks and the father with disorderly conduct before the couple, who are not legally married, moved to California a year ago.

Hinshaw said the report left the impression "that physicians and hospital staff might take advantage of people who might be in difficult circumstances to wrest" from them consent for an experimental operation. He said that he did not know the parents' background or marital or financial status and that the information would have made no difference in the hospital's handling of the case.

Hinshaw indicated that the hospital will continue to refuse to release the informed-consent statement signed by the parents or make the leading transplant surgeon, Dr. Leonard L. Bailey, available for an interview on what he told the parents about the operation and possible alternative procedures.

Hinshaw declined to answer a question about earlier, apparently erroneous, statements by Bailey concerning an operation available in Philadelphia and Boston to attempt to fix hearts with Baby Fae's deformity. He declined to say what the parents were told about the cost of the baboon heart transplant, which is being paid for by the hospital, and the cost of any alternative.

Hinshaw said Bailey expects several rejection episodes in the first three months after a transplant. "We don't think there has been permanent damage" from the first episode, Hinshaw said, "but that is a possibility. Any rejection episode, if it becomes particularly severe, may leave damage behind."

Experience with Baby Fae, who weighs about 5 pounds, 3 ounces, indicates that heart transplants between different species may be no more difficult than human-to-human transplants, given an infant recipient with a poorly formed immune system and new kinds of immunosuppressive drugs, Hinshaw said.

The rejection episode also indicated to doctors that they should have been giving the child a higher dose of a sophisticated new immunosuppressant, cyclosporin-A, and fewer antibiotics, which might have helped trigger the rejection.

Hinshaw said the rejection episode began Friday but did not become apparent until the next day.

Doctors increased doses of cyclosporin-A, put the baby back under an oxygen tent, and "it looked like it was turning around," Hinshaw said. But Monday morning, doctors detected "a certain stiffening of the heart," he said; the heart continued to beat at a normal rate "but the beat was not as effective in pushing the blood." This, in turn, was slowing the work of the kidneys and the production of urine to clean the body of wastes.

Doctors resumed feeding the baby intravenously and reinserted an artificial respirator tube to save energy she had been using digesting formula and breathing. They gave her the drug digitalis to stimulate the heart, and a new, potent immunosuppressant, lymphocyte immune globulin, to fight rejection. Antibiotics were cut off and steroids reduced.

Hinshaw indicated that the baby was not "her usual exuberant self" during the episode, but said she did not appear "in any great pain."

Doctors decided not to perform a cardiac biopsy, a proven method to determine the extent of a rejection episode. Hinshaw said doctors feared that "with the heart so small and so thin, there might have been a technical accident." An electrocardiograph was used to check the heart's action throughout.

A hospital statement today said the baby's blood pressure, heart rate and heart rhythm were normal, and she was "active and alert." It said that the peak of the rejection episode was Monday evening, and that the baby "is now showing subtle but definite signs of early recovery."