Professors from the Harvard School of Public Health and Brown University released a study on Monday pointing to a “potential causal relationship” between smoking during pregnancy and criminal behavior among offspring later in life.

The authors—including  Angela D. Paradis of the Harvard School of Public Health and Stephen Buka, a professor of community health at Brown University—tracked over 4,000 pregnancies in Rhode Island between 1959 and 1966, collecting information on the mothers’ smoking habits.

In 1999 and 2000, the researchers checked the criminal records of 3766 of the now-adult children.

According to the study, “[t]he offspring of mothers who smoked heavily during pregnancy had a 47% increased odds of multiple versus no arrests.”

These findings highlight the costly impact of smoking while pregnant, Buka said.

“There seems to be consistent and somewhat surprising long-term effects on aggression, criminality and violence that we don’t fully understand but that seem real,” he added.

The study controlled for several other variables, such as income level and maternal IQ, and found that a strong association between smoking and crime remained.

However, Paradis said, smoking mothers “tend to be younger moms with less education from poor neighborhoods,” and so the problem disproportionately affects low-income groups.

The findings offer a glimpse of hope for future generations, Paradis said, adding that repeat-criminals are “very expensive to society,” and maternal smoking is “potentially modifiable.”

Other long-term studies are also examining which environmental factors predispose children to such behavior. The federal government is currently undertaking the largest to date—the National Children’s Study, which follows 100,000 children from their prenatal stage through their twenty-first birthday.

Researchers like Paradis and Buka hope that the discovery of factors that cause violent crime will lead to programs that are, as Paradis said, “sensitive to people most at risk.”