Everyone knows that expectant moms who smoke risk damaging their babies’ physical health. New evidence from a Danish study shows that smoking can also harm babies emotionally. Patricia Brennan of Atlanta’s Emory University has found that the more cigarettes a woman smokes in the third trimester of pregnancy, the more likely her children are to be arrested for a crime or hospitalized for substance abuse.

Of course, the study shows only a statistical association between maternal smoking and delinquency. Brennan concedes that other factors may have contributed to the children’s problems. The study’s subjects were born in a hospital located in a depressed part of Copenhagen, Denmark, so many of the mothers were relatively poor and might have been under stress that could have harmed their children.