A diagnosis of attention-deficit/hyperactivity disorder (ADHD) in children may be related to their mother's smoking during pregnancy. The study, reported in Pediatrics (August 2005), used data from the Danish government's longitudinal registers on 4000 children born between 1991 and 1994. The researchers compared smoking habits of the mothers of 170 children who were later diagnosed with ADHD with 3765 mothers whose children were not diagnosed with the condition.
The researchers controlled for low birth weight of babies, poor newborn health status, young maternal age, and low socioeconomic status. They found that smoking mothers were almost 2 times as likely to have children with ADHD, compared with mothers who did not smoke during pregnancy. Of the participants, 59% of the mothers of ADHD children smoked while pregnant, compared with 35% of the mothers with non- ADHD children. One key factor that could not be determined was whether pregnant smokers had ADHD themselves, which might make them more likely to smoke, and which might be the reason for the higher number of children with the disorder in this group.