ADHD and Fetal Exposure to Teratogens

This question comes from a young couple in Georgia –

Dear Dr. Pandit, My husband and I are both taking a class in child development because we are expecting our first child.  This week we were discussing teratogens.  Someone in class said that ADHD is caused by teratogens. Is this true? If so, what kind of substance is causing ADHD? Or is it just anything that is a harmful substance?  With both of us in school it is stressful enough, and now with this to worry about, I am having trouble concentrating on anything else!

from Just Pregnant in Georgia

Hello Just Pregnant!

Your question kind of leaves me wondering who you might have for a professor -  teratogens (harmful substances that a fetus may be exposed to), can be anything from drugs to air pollution to the stress an expectant mom is under during her pregnancy.  There isn’t any research that confirms a teratogen as a cause for ADHD, however I do know of some studies that have linked both smoking and stress to ADHD. Smoking during pregnancy is associated with low birth weight, preterm delivery, infant death, childhood asthma, and learning difficulties. In one study, Thapar and colleagues (2003) recruited 1,452 twins between the ages of 5 and 16 years and collected the following information: family history of ADHD, parent and teacher ratings of children’s ADHD symptoms, maternal smoking during pregnancy, conduct disorder symptoms, and aspects of family adversity like poverty and single-parent households. Although family history mostly accounted for ADHD in children, smoking during pregnancy remained a significant predictor, even after controlling for conduct disorder and family factors.

Linnet and colleagues (2003) reviewed literature on the relationship between prenatal exposure to nicotine, alcohol, caffeine, and psychosocial stress and a child’s developing ADHD symptoms. The review included 24 studies on nicotine, 9 on alcohol, 5 on psychosocial stress, and 1 on caffeine. Smoking during pregnancy showed a moderate risk for ADHD symptoms in childhood. Results from studies on psychosocial stress were inconsistent, but indicated a possible link between high levels of maternal stress during pregnancy and ADHD in children. Taken together, these findings suggest that prenatal exposure to nicotine and to maternal stress may contribute to the development of ADHD symptoms in childhood. But consider that more research is needed in order to rule out other maternal lifestyle factors that might explain these associations. If you want to be safe for now – avoid smoking and perhaps learn some meditation techniques to deal with stress more effectively.  Keep me posted on your stress reduction. 

Warm regards,

Dr. Pandit