Experts on infant health told a congressional oversight committee yesterday that America's hospitals are reporting startling increases in the number of babies who are born physically and mentally damaged because of their mothers' use of PCP, cocaine and other substances, including tobacco and alcohol.

Although national health registries do not require doctors to report cases of infants damaged by parental drug exposure, doctors from New York to Seattle described the grim results of epidemic drug use colliding with a baby boom, including hundreds of babies who have contracted AIDS in utero from their drug-abusing mothers.

In New York City, where the increase has been best documented, health officials found 884 addict births in 1983, nearly 8 of each 1,000 live births. In 1966, the first year that the New York Health Department calculated the rate, there were 227 addict births, or 1.5 of each 1,000 live births.

At Martin Luther King-Drew Medical Center in Los Angeles, 226 infants with drug problems were treated last year, compared with 28 infants in 1982, according to Dr. Xylina Bean. She said hospital records for the first four months of this year already show 155 babies treated for drug addiction, most of them cocaine.

"We're being left saddled with infants and the mothers leave to continue their drug-abusing lives," said Dr. Ira Chasnoff, director of Northwestern University Hospital's Perinatal Center for Chemical Dependence in Chicago. He said that drug-addicted infants typically spend four to six weeks in intensive care at a cost of $28,000.

"We've had two cases where babies suffered a stroke in utero from their mother's use of cocaine," Chasnoff said, adding that urine testing of mothers ready to deliver showed 3 percent of the women had used drugs such as Valium, PCP and marijuana within 24 hours before the test.

"In the last two and three years, we've seen younger women with more middle-class backgrounds, women from the North Shore, Winnetka, Wilmette where cocaine is served at afternoon teas," Chasnoff said. "We've seen college girls who are pregnant who used cocaine at their sorority house."

Chasnoff also told the House Select Committee on Children, Youth and Families that the university hospital has found a link between users of cocaine and sudden infant death syndrome, with 15 percent of the babies of its cocaine-using patients dying from SIDS.

Benjamin Walker Jr., director of the Odyssey Foundation in New York, which operates a home for addicts and their children, advised that drug education begin in preschools because youths are reporting their younger siblings are smoking cigarettes laced with "crack," a potent form of cocaine.

"We're finding a new phenomenon where 6- and 7-year-olds are becoming addicted to crack," Walker said. "It's available for school lunch money, $1 or $1.50 a cigarette."

Walker said family histories taken of each of the home's 45 children revealed the grade school drug use, information that was given to the city's Bureau of Child Welfare.

Dr. James Oleske, director of the pediatric AIDS unit at Children's Hospital in Newark, criticized the lack of federal and health insurance money to treat children with acquired immune deficiency syndrome. Many initial cases of pediatric AIDS were caused by impure blood transfusions, but blood screening tests have reduced that risk. Most cases today are from women who use intravenous drugs or whose sex partners use drugs or have homosexual contacts.

"We're not having any movie stars giving benefits for children dying of AIDS from drug-addicted parents," Oleske said, noting that hospital registries show about 2,000 cases of children with AIDS nationwide.

Figures used by the federal Centers for Disease Control count only 364 of the cases because the CDC definition requires children to develop some symptoms found more frequently in adults.

Oleske said studies show that 70 percent of drug-abusing women in New Jersey test positive for AIDS exposure and have a 50 percent chance of bearing a child with AIDS. "If you thought you had troubles now," he told fellow panel members, "wait until your same [drug-abusing] population starts developing AIDS . . . . "

Committee members met at Children's Hospital National Medical Center in the District, where committee members viewed several infants less than two pounds fighting for their lives.

Doctors at the hospital said narcotic withdrawal did not affect any of the babies seen by the representatives, but said dozens of drug-addicted infants are treated in the intensive care nursery each year. "We get several [sick] babies every week in Washington from alcoholic mothers," said Dr. Kenneth Rosenbaum of the hospital staff.

National increases in drinking and smoking among women of child-bearing age are causing more babies to be born with low birth weights, according to Rep. George Miller (D-Calif.), the committee chairman. "For those who survive, we know that they will be at much greater risk of disease and developmental handicaps, like cerebral palsy and mental retardation," he said.

Locally, Joyce Thomas, director of Children's Hospital's child protection division, reported that PCP-intoxicated parents are causing an increased number of the 600 child abuse cases seen each year at the hospital.

"These cases have included a mother who attempted suicide and mutilation of her infant, a PCP-intoxicated mother who gave her 2-month-old infant an overdose of cough medication, PCP-using parents who dropped a television on their 2-week-old infant during a fight and a 21-day-old premature infant who stopped breathing after her intoxicated father held her upside down," Thomas said.