"They can look jittery, very lethargic. They have alternating states. There is a rigidity in muscle tone. What I mean is, it's like a lead pipe."

Dr. Judy A. Howard of the University of California at Los Angeles was describing the limbs of 6-month-old children of cocaine users.

Of the first dozen so-called "cocaine babies" she saw last year, five had "dismorphic" facial features, a deformity that indicates severe retardation and cerebral palsy. "The ones that escape the dismorphic features," Howard said, "are going to have, I believe, some kind of learning disability."

Children affected this obviously, she said, are offspring of "heavy, heavy users. These are not just an occasional snort." As with many substances that affect fetuses, the effects of smaller doses are more subtle and difficult to detect.

Delivery room nurses are usually the first to notice drug abuse by the mother, Howard said, often by seeing needle marks on her arms. At that point, the newborn is "automatically bagged" -- given a urine test for drugs.

At UCLA, a team of child abuse specialists is asked to intervene in these cases under California law, and the infants are usually placed in foster homes. This has allowed Howard and her colleagues to follow the children and trace their development.

The muscular rigidity, even at 8 months of age, indicates that the nervous system is not developing properly, she said. One explanation is that cocaine, which constricts blood vessels, prevented blood from reaching the fetal brain, impeding development. Another is that, as in the addicted mother, the infant's system of brain chemicals is disturbed.

"Will the system ever kick in? I don't know," Howard said.

Howard and her colleagues also have measured the infants' brainwave responses to visual stimulation, another test of development. "The cocaine babies had abnormal waves," she said. "They're seeing something, though. It's not like they're blind."

But she added: "At 5 months old, we're still getting these abnormal waves."

In many cases, cocaine users also drink alcohol during pregnancy, and some of the symptoms in the infants mimic fetal alcohol syndrome, a well-documented birth defect in children born to alcoholics. "I don't know if it's [cocaine]," Howard said, "or the alcohol."

The number of people calling a national cocaine hotline for information on the effect of cocaine on offspring has increased from one call a month to at least 12 and usually more, the American Academy of Pediatrics reported in its monthly newspaper, Pediatric News.

The instances of cocaine babies seem to cross economic lines. "This is UCLA, adjacent to Beverly Hills. We're all quite surprised about this," Howard said. "So far we've identified 30 to 35. I'm sure we're not getting them all."