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Smoking While Pregnant May Increase Risk of ADHD in Child

By Evan Wiley

Smoking cigarettes is bad for your health and the health of those around you, in ways almost too numerous to count.  However, some mal-effects get less attention than others. While we have all heard of lung cancer and premature aging, consider this little known fact.  A woman who smokes while pregnant increases the likelihood her child develops attention-deficit/hyperactivity disorder (ADHD). Researchers have two possible explanations for this finding. One is that when cigarette smoke enters her body upon inhalation, its chemicals reach the fetus and affect development.  Another hypothesis suggests that it is genetics, not the chemicals in cigarettes, that accounts for the increase in ADHD. In other words, it’s not the smoke that causes the ADHD; the genetic trait that makes someone more likely to smoke also makes it more likely that person will pass ADHD to offspring.   A group of researchers sought to find whether cigarette smoke or the genetics of a parent has the greater effect on the development of ADHD in children.

Using surveys, researchers gathered information about whether or not children developed ADHD as well as information about the parents’ smoking habits (or lack thereof). To estimate the effect of genetics, they considered only the cases where the father smoked but the mother did not. Since nicotine and other chemicals found in the father’s blood would not affect the developing fetus, the rate of ADHD in those children gave some idea as to the influence of genetics (the father’s genetics would still affect the fetus). The researchers assumed that a mother and father’s  genetic influence on the inheritance of ADHD is equal, which is a safe assumption to make. In cases where the mother smoked but the father did not, the chemicals from smoking and the mother’s genetics would both influence whether or not the child got ADHD.

Researchers found that while genetics is important, smoking while pregnant significantly increases the risk of a child developing ADHD. Interestingly, the increased risk was still present when the mother stopped smoking and instead used a nicotine patch, though it was not as risky as continued smoking. This suggests that nicotine itself is one of the chemicals in cigarettes that can increase the risk of a child later developing ADHD.

What does this mean for you?

There are two main things to take away. The first is well known:  it is best for a child’s health if the mother does not smoke while pregnant. The second is that using a nicotine patch or nicotine gum while pregnant may increase the risk of the child developing ADHD.  While not smoking is the ideal option, using a nicotine patch or gum is still a healthier choice than smoking, for both the mother and the child.

 

Reference:

Zhu J, Olsen J, Liew Z et al. Parental Smoking During Pregnancy and ADHD in Children: The Danish National Birth Cohort. Pediatrics Vol. 134 No. 2 August 1, 2014 pp. e382 -e388