Blaming such problems on prenatal cocaine use alone has unfairly stigmatized children, creating an unfounded fear in teachers that "crack kids" will be backward and disruptive, according to the study, an analysis of 36 previous studies.
"I'm not trying to be Pollyanna-ish and say there are not problems" with cocaine use by pregnant women, said Dr. Deborah A. Frank, an associate professor of pediatrics at Boston University who led the analysis. "I'm saying there are many more serious risks to children's development."
The analysis appears in Wednesday's Journal of the American Medical Association.
The perception that crack babies are a unique phenomenon stems from an overreaction to research that did not adequately take into account such factors as family environment and cocaine mothers' use of other substances while pregnant, the researchers said.
Women who use cocaine while pregnant often smoke, drink, take other illegal drugs and live in poverty or otherwise unhealthy environments.
These factors can explain all or some of the problems once solely blamed on cocaine's presumed effects on the developing fetus, such as low birth weight, small head size, low scores on mental-development tests and behavioral problems such as attention deficits, the researchers said.
Alan Leshner, director of the National Institute on Drug Abuse, said that while researchers believe the effects of prenatal cocaine exposure "are not nearly as dramatic as people initially thought," the study should not be misinterpreted to suggest that cocaine during pregnancy isn't harmful.
"Most of the effects are thought to be on behavioral characteristics, most of which won't be apparent until kids are getting older," Leshner said.
Whether prenatal cocaine use can cause developmental problems that do not appear until after age 6 or at puberty is being studied.
In an accompanying editorial, Dr. Wendy Chavkin of Columbia University said the crack baby "has become a convenient symbol for an aggressive war on drug users because of the implication that anyone who is selfish enough to irreparably damage a child for the sake of a quick high deserves retribution."
"This image, promoted by the mass media, makes it easier to advocate a simplistic, punitive response than to address the complex causes of drug use," she said.
The JAMA study follows last week's Supreme Court ruling barring public hospitals from testing pregnant women for drugs and giving the results to police without consent.
That case involved a South Carolina hospital's now-abandoned drug-testing policy, esigned to stop pregnant women from harming fetuses by using crack. It resulted in 30 arrests.
Frank was among doctors and medical groups, including the American Medical Association, who filed briefs opposing the drug-testing policy.
Pharmacologist John A. Harvey, co-editor of a 1997 New York Academy of Sciences report that linked prenatal cocaine exposure with subtle neurological damage, said Frank's review muddles science with politics.
"They play up the problems of tobacco and alcohol very appropriately and then they say, 'Well, cocaine is no worse,' " said Harvey, of MCP Hahnemann University in Philadelphia. "Well, that makes it pretty bad."
Smoking and drinking during pregnancy have been linked to developmental and behavioral problems in children.
Animal studies suggest cocaine use alone in pregnancy hampers nerve cell development in the fetal brain, resulting in behavioral problems that get worse with age, Harvey said.
By LINDSEY TANNER