CHICAGO, DEC. 5 -- Nursing mothers who take cocaine run a high risk of feeding the drug to their babies through their breast milk, with possibly fatal consequences, pediatricians warned today.

A case study in the journal Pediatrics is the first official report of infant cocaine intoxication through breast-feeding, but doctors said several similar incidents have oc-curred, including one case in which a Detroit infant died after being suckled by a woman who had smoked "crack," a potent form of the drug.

"I always tell pregnant women, 'Remember, whatever you put into your bodies you put into your baby,' " said Dr. Ira Chasnoff, of Northwestern Memorial Hospital. "Now that goes for nursing women, too."

Chasnoff reported on a case of a woman who was an occasional cocaine user, but had given up the drug during pregnancy and resumed use a week after the birth of a girl.

When the baby was 2-weeks-old, the woman inhaled about a half gram of cocaine over a four-hour period, in which she breast-fed the baby five times.

The baby soon became irritable, began vomiting and having diarrhea. The woman brought the baby to the emergency room when the baby's eyes became dilated and would not focus on the mother's face.

Significant levels of cocaine were found in the mother's milk three days later, and the baby still showed cocaine in her urine 60 hours later, Chasnoff reported. However, the baby suffered no permanent ill effects and is doing well nearly a year after the incident.

"She was lucky," Chasnoff said. "And remember, this mother wasn't a drug addict, in any traditional sense."

In another incident in July, a 2 1/2-month-old Detroit baby died after ingesting cocaine-tainted breast milk, said Dr. L.J. Dragovic, Wayne County medical examiner. The case is being investigated by the prosecutor's office, he said.

Dragovic would not identify the woman, but said she had a long history of drug abuse, and that the baby girl had been born with cocaine addiction syndrome, a complex of nervous and physical disorders similar in many ways to the better-known fetal alcohol syndrome.

In both syndromes, babies tend to be smaller, crankier and appear to suffer developmental problems as they grow older.

Chasnoff said he has seen several cases of cocaine intoxication through breast-feeding.