Patricia A. Brennan, PhD, assistant professor of psychology at Emory University and her colleagues at Emory and the University of Southern California studied 4,169 males born in Copenhagen, Denmark, between 1959 and 1961. During their pregnancies the mothers kept a daily record of their smoking habits, including the number of cigarettes they smoked each day. Thirty-four years later, researchers checked the criminal records of the male offspring of the women who kept a journal of their smoking habits.

"Our results support the hypothesis that maternal smoking during pregnancy is related to increased rates of crime in adult offspring," the researchers wrote in their study.

Their findings were published in the March 1999, issue of the Archives of General Psychiatry. The researchers found a relationship between the amount a mother smoked and arrests for both violent and non-violent crime. They also noted that mothers who smoked during pregnancy seemed to have sons who would later show persistent criminal behavior.

The researchers concluded prenatal smoking is a predictor of habitual criminal behavior. However, they said more research is needed to investigate the link between psychological effects or damage to the fetus?s brain from prenatal smoking and criminal outcomes.

"We know that smoking during pregnancy can have a number of negative physical effects on the fetus, such as low birth weight," said Dr. Brennan. "The message here is that smoking during pregnancy could have longer-term ramifications."

When comparing men whose mothers did not smoke during pregnancy with men whose mothers did smoke, the latter group was 1.6 times more likely to be arrested for non- violent crimes, twice as likely to be arrested for violent crimes, and 1.8 times more likely to be involved in a lifetime of criminal behavior.

According to Dr. Brennan, the researchers tried to factor out other influences, such as drug use during pregnancy, father?s history of criminal behavior, and socioeconomic status.

In the report, Dr. Brennan and her colleagues speculated damage to the fetus?s nervous system could be to blame for the negative behavioral effect. But she is quick to point out they are not saying smoking during pregnancy is a direct cause of criminal behavior.

An indirect link could also explain the findings. For example, mothers who were heavy smokers may have been more likely to have certain behavioral characteristics that adversely affected their son?s behavior.

Other opinions
Douglas Hoffman, PhD, an associate professor of pathology and psychiatry at Dartmouth University and a researcher for Smoke-Free Families, believes the study is flawed because it passed over other factors that may influence criminal behavior. Dr. Hoffman said crime is more likely the result of environment. "What I see from this study is the shaking down of a correlation [between prenatal smoking and criminal behavior] from a large data set."

"The study is provocative," said Frank Baker, PhD, a psychologist and director of the behavioral research center at the American Cancer Society. "It fits into a growing body of evidence that points to the risks of smoking during pregnancy. It makes some associations [between smoking and crime], but I don?t think we can talk about cause and effect [yet]."

While Dr. Baker was cautious about the implications of the findings, he agreed based on past studies smoking might have a relationship to criminal behavior. While the homogeneity of the Denmark population may have accounted for large differences in socioeconomic status, poverty is a factor too important to dismiss.

"If it were an isolated article, it might not be accepted," Dr. Baker said. "The message here is this is further evidence that smoking during pregnancy is risky behavior."

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