Smoking While Pregnant Linked to ADHD in Children
Expectant moms' use of nicotine-replacement therapy could also spell problems for kids, study suggests
Previous research has already linked ADHD in children to mothers who smoked during pregnancy, noted Wilens, who was not involved with the study.
In the new study, researchers examined the medical records of nearly 85,000 children born in Denmark to mothers who were recruited to be part of the study from 1996 to 2002.
Signs of ADHD were present in slightly more than 2,000 children. The numbers were lower among kids of nonsmoking parents (1.8 percent) and in households where mom quit smoking and dad was a nonsmoker (2 percent). The rates of ADHD were highest among kids in families in which both parents smoked -- 4.2 percent.
Among those whose fathers didn't smoke, ADHD rates were highest among those whose pregnant mothers were on nicotine-replacement therapy (3.8 percent) or were smokers (3.4 percent). In households where the father smoked and the mother was on nicotine-replacement therapy, rates of ADHD in children were 2.9 percent, according to the study.
The researchers cautioned that the number of pregnant mothers on nicotine-replacement therapy in the study was small -- just 29 mothers of children with ADHD used these products during pregnancy. As a result, "the findings are more uncertain," Zhu said. In another caveat, the study authors noted that many parents and kids didn't take part in a seven-year follow-up designed to monitor how the children were doing.
Still, there are many good reasons to stop smoking before conceiving, the experts said.
"If at all possible, try not to smoke when conceiving," Wilens said. "If you think you've conceived and you're smoking, it's best to come off cigarettes as quickly as possible. If you need to use nicotine-replacement therapy, use it for as short a time as possible."
The good news is that smoking prior to pregnancy doesn't seem to boost the risk of ADHD in the unborn child, he said.
The study was released online July 21 in advance of publication in the August print issue of the journal Pediatrics.