(WEHT) – Research has shown there is a correlation between the month a child is born and the likelihood they will get diagnosed with ADHD.

Norwegian researchers analyzed data from half a million children over a decade. They found children who are the youngest in their class were 80% more likely to receive an ADHD diagnosis than their older peers.

Researchers reported that 5.3% of boys born later in the year in October to December, had received ADHD medicine in comparison to 3.7% of boys who were born earlier in the year, in January to March. Furthermore, the percentages for the girls in the study showed that 2.2% of the later born girls received ADHD medication compared to 1.3% of the earlier born girls who received the medicine.

Researchers say, studying this by grade showed an increased risk for later born children, starting at grade 3 and up.

However, the authors of the study warn of the dangers of overprescribing ADHD to children who are immature and unfairly compared to their oldest classmates.

You can read the study here.