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Member Research & Reports

Member Research & Reports

Columbia: Maternal Smoking and the Risk of ADHD

A recent study strengthens the link between maternal smoking and later development of attention-deficit/hyperactivity disorder (ADHD) in children, and is the first to show that heavier smoking may increase these odds. Dr. Alan S. Brown, professor of epidemiology at Columbia University Mailman School and professor of psychiatry at Columbia Medical Center and the New York State Psychiatric Institute (NYSPI), is senior author.

Previous studies have linked maternal smoking while pregnant to development of Attention Deficit Hyperactivity Disorder (ADHD), but those reports relied on maternal self-reporting. The study, in Pediatrics, measured actual levels of cotinine in the mother’s blood while pregnant.

Of women who gave birth in the U.S. in 2016, 7 percent self-reported smoking cigarettes during their pregnancy, but studies have shown that self-reporting underestimates smoking prevalence by 8 percent to 28 percent.

This research analyzed cotinine levels to determine maternal smoking habits. Cotinine, the byproduct of nicotine after it is metabolized in the liver, stays in the body longer and can also enable researchers to quantify nicotine exposure by the level — even detecting passive smoking.

The study used a database in Finland of blood samples stored from pregnant mothers, then investigated which children developed ADHD. Results from more than 1000 infants later diagnosed with ADHD were analyzed against their mother’s blood samples from pregnancy, comparing them against an equal number of controls. Researchers found that the mothers whose children were later diagnosed with ADHD had a mean cotinine level that was more than double the level in mothers whose children were not diagnosed with ADHD.

The paper also shows a dose-response to cotinine levels, with the likelihood of ADHD development increasing with higher maternal cotinine levels.

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