Children born to women who smoke cigarettes during pregnancy, especially when mothers are heavy smokers, are at an increased risk for attention-deficit/hyperactivity disorder (ADHD), a new review of medical studies confirms...An increased risk of ADHD for children of women who smoke while pregnant has been reported before. What’s new here, the authors say, is that the data have been pooled from studies in multiple countries and time periods, and also that as the daily tally of cigarettes went up, the risk of ADHD went up.