PARIS — Mothers who puff a pack a day or more while pregnant run a 30-percent higher risk of having kids who become criminal offenders, according to a study published Tuesday. The link held true even after other factors statistically associated with criminal behavior — mental illness, family problems, poverty — were ruled out, the study found. Women were as likely as men to tend toward crime, and both sexes faced a higher risk of frequent arrests when their mothers were especially heavy smokers, it said. Researchers led by Angela Paradis of the Harvard School of Public Health reviewed the health and criminal records of 4,000 American adults between 33 and 40 years old. The men and women were part of a long-term health study in Rhode Island designed to track the long-term effects on children of conditions during pregnancy and around birth. Information was collected about the smoking habits of the mothers, who were enrolled in the study between 1959 and 1966. Children whose mothers smoked at least 20 cigarettes per day while expectant were 30 percent likelier to end up with a criminal record, and were also likelier to be repeat offenders. “While we cannot definitely conclude that maternal smoking during pregnancy — particularly heavy smoking — is a causal risk factor for adult criminal offending, the findings do support a modest causal relationship,” the authors concluded. Previous research has shown a strong correlation between mothers who smoke while pregnant and a range of problems in children, including hyperactivity, poor attention span and aggressiveness in early childhood, and delinquency in adolescence. Animal studies suggest that these problems may stem in part from the biological effects of nicotine on the developing brain, especially on neurotransmitter receptors. Chronic criminal offenders are more likely to suffer from neuropsychological disorders. The research appears in the Journal of Epidemiology and Community Health, published by the British Medical Association (BMA).