An alarming number of babies were exposed to drugs in the womb, according to researchers who found the problem not confined to inner cities and warned that a "generation of innocent addicts" was being created.

The study by the National Association for Perinatal Addiction Research and Education found that at least 11 percent of women in 36 hospitals had used illegal drugs during pregnancy.The hospitals were chosen to represent institutions of varying sizes with patients from varied socio-economic levels, said Dr. Ira J. Chasnoff, who directed the survey.

The study, financed by the federal Office of Substance Abuse Prevention and the March of Dimes Birth Defects Foundation, showed the incidence of substance abuse among women in the hospitals surveyed ranged from four-tenths of 1 percent to 27 percent of pregnant patients.

Chasnoff said Monday the differences often reflected how carefully the hospitals looked for the problem, with those hospitals with an established system of determining drug abuse among pregnant women finding considerably more instances.

Substances in the survey included cocaine, marijuana, heroin and methadone, amphetamines and the hallucinogen phencyclidine, or PCP.

Chasnoff said the high rate of pregnancies or births in which drugs are present is not confined to the largest urban areas but is similar in hospitals across the nation.

He also said damage to the baby from the drugs could include prenatal strokes, lasting brain damage, seizures after birth, premature birth, retarded fetal growth, breathing lapses, absence of part of the intestines or structural abnormalities in genital and urinary organs.

Researchers said the illegal drug use in pregnancy cuts across racial and socio-economic lines and maternal age groups, especially since cocaine has become so popular.