It’s been a puzzle for many parents in the past few decades: Just what causes attention-deficit/hyperactivity disorder (ADHD), anyway? It can be difficult to watch your child struggle in school, with friendships, and in their hobbies as they deal with the challenging symptoms of ADHD, including impulsivity and inattentiveness.
Increasingly, researchers are gathering more info on potential causes of ADHD. One study released in March 2019 has strengthened the evidence against one particular risk factor: smoking during pregnancy.
The study included over a thousand patients born in Finland between 1998 and 1999—and their mothers. Instead of asking the mothers if they smoked, researchers tested cotinine levels in the mother’s blood.
Cotinine is a chemical produced in the body when you’re exposed to nicotine, according to the Centers for Disease Control and Prevention (CDC). It lingers in the body longer than nicotine does, so it’s one of the best ways to test for nicotine exposure (either from smoking or from secondhand smoke).
Doctors tested the cotinine levels during the first and second trimesters, and then compared those findings with ADHD statistics as the children aged. Researchers then sorted the mothers into three groups, from lowest to highest nicotine exposure. As it turns out, the more cotinine the mother had in her blood during the first and second trimesters, the higher the risk of ADHD in her offspring.
Drug and alcohol use during pregnancy has long been a suspected cause of ADHD, and the new study shows the dose-dependent link between smoking during pregnancy and ADHD risk. In other words, heavier smoking results in a higher risk of ADHD. In fact, kids born to mothers in the group with the heaviest nicotine exposure had double the risk of developing ADHD. This link was true regardless of the parents’ age or socioeconomic status, which are other factors that can impact childhood health.
Besides the risk of ADHD, smoking during pregnancy can affect the health of both the mother and baby in a number of ways. Other risks to the infant include preterm birth, low birth weight, and birth defects, according to the CDC. Babies who are born below the typical birth weight are more likely to have trouble fighting infections, eating, and gaining weight, and they are more at risk for devastating complications like sudden infant death syndrome (SIDS).
