Low birth weight has long been known to be risk factor for behavioral problems like ADHD in children. The circumstances at birth, the immaturity of the brain, and social factors have been regarded as possible explanations. The dissertation shows that iron deficiency during the first half-year of life can be a major cause. Low birth weight as such means that the child is born with smaller reserves of iron, which is a key building block in all cells in the body. However, it has long been unclear whether the risk of iron deficiency also applies to healthy children with only moderately or marginally low birth weights.
The dissertation studies 285 otherwise healthy children with marginally low birth weight, between 2 000 and 2 500 g. The children were randomly selected to receive or not receive iron supplements during the first half-year of life. The results showed that those who had been given placebo, compared with those who had received an actaul iron supplement, evinced a clearly higher risk of iron deficiency at the age of 6 months and moreover a four-times-higher risk for behavioral problems at the age of 3 years.
The researchers draw the conclusion that all children with a birth weight under 2 500 g should be offered iron supplements, regardless of whether the cause of their low birth weight was premature birth or poor fetal growth.
The study, which was conducted in Umeå and Stockholm, is directed by Associate Professor Magnus Domellöf in collaboration with researchers from the Karolinska Institutet.