ADHD risk rises with degree of prematurity, study suggests

Children born prematurely appear more likely to be diagnosed with ADHD. This we knew. Now researchers have established that a greater risk exists even for babies born moderately early -- and that the size of the risk is associated with the level of prematurity.

That is, the earlier the birth, the higher the likelihood of being diagnosed with attention-deficit hyperactivity disorder, or more specifically, of being prescribed medication for attention-deficit hyperactivity disorder. The findings were reported online Monday in Pediatrics.

But don’t assume that your premature child is fated to have the condition. Getting a prescription isn’t a precise proxy for actually having the attention disorder, and the difference in risk for any individual child isn’t enough to suggest that doctors should automatically get the prescription pad ready at birth.

Overall, the study flags the potential for problems and suggests that premature children be closely monitored as they develop.

Using a Swedish drug registry, Swedish researchers used birth records to link which children ages 6 to 19 had been prescribed medication for ADHD. About 1.2 million children were included in the analysis.

The earliest-born children were about 2 1/2 times more likely than their full-term peers to be on medications -- about 16 in 1,000 of babies born between 23 and 28 weeks compared to six in 1,000 babies born between 39 and 41 weeks.

Even after researchers adjusted for factors such as socioeconomic status and maternal smoking, the earliest-born babies were twice as likely to be prescribed ADHD medications than their full-term counterparts.

Notably, children born moderately prematurely were also more likely to be taking ADHD medication, compared to their full-term peers. And the later the birth, the lower the likelihood of being prescribed medication, the study found.

Of course the results come with a caveat: The study didn’t establish how many children have ADHD. It established how many children were prescribed ADHD medication. The authors say guidelines have existed in Sweden since 2002 to ensure only the most severe cases are prescribed medication.

But even if ADHD is as prevalent as the medications suggest, only 1.6% of children born prematurely would have the disorder, compared to 0.6% of full-term babies. The risk is small either way.

Further, some research suggests that ADHD may not be a permanent condition. In short, kids may grow out of it. In one study, Finnish researchers followed 457 children into adulthood—188 of whom had “probable or definite ADHD”—and found that the fidgety, stereotypically ADHD children were the most likely to mature out of the disorder.