Health at birth linked to ADHD risk

A baby's health in the first minutes after birth may be linked to his or her risk of developing attention-deficit hyperactivity disorder (ADHD) later on, a condition that involves attention problems and impulsive behaviour.

Both preterm birth and a low Apgar score may be markers of less-than-optimal fetal development. The Apgar score assigned to all newborns in the first five minutes of life is based on several physical signs, including breathing, heart rate and muscle tone. A score of 7 or higher is considered normal, with a 9 or 10 indicating that the baby is in the "best possible condition."

To examine whether low Apgar scores at 5 minutes are associated with higher risk of ADHD, researchers studied the data from Danish national registry data for 980,902 children born between 1988 and 2001. Of those children, 8,234 were diagnosed with ADHD - most of them boys.

Even after the researchers accounted for factors like preterm birth, family income and mothers' smoking and education levels, the risk of ADHD was higher among kids with Apgar scores below 7. Still, the vast majority of children in the study were not diagnosed with ADHD, regardless of Apgar score. And it's not clear whether the Apgar-ADHD link might eventually have any practical implications.

A number of studies have linked preterm birth to an increased risk of ADHD, although the reasons aren't clear. An abnormal Apgar score could reflects some sort of stress during pregnancy or birth - like decreased oxygen supply - that might contribute to ADHD development in the years ahead. Future studies are required to undercover the reasons for the link between Apgar score and ADHD. Large population studies might also be able to look at how combinations of factors - like low Apgar score plus a family history of ADHD - come into play.