The study comprised more than 12,500 children in Sweden, Finland, and Denmark. “Many children are being diagnosed with ADHD and at the same time there is an epidemic of obesity in the world, with more and more women already overweight at the time they become pregnant. If it turns out that the mother’s weight is of significance and, together with other factors, can influence ADHD-like symptoms in the child, we have not only found a contributory cause but also a potential avenue for preventive work that can enhance the well-being of both mother and child,” says Alina Rodriguez at the Department of Psychology, Uppsala University, who is the lead author of the article.

The children were monitored from their time in the womb up to school age, when their teachers were asked to answer a questionnaire about the child’s behaviour. Roughly one out of ten children had marked difficulties with their attention span and with hyperactivity. “How many of them actually have ADHD cannot be determined solely on the basis of the questionnaire responses, however,” explains Alina Rodriguez.

The correlation between mothers’ body mass index and child symptoms was found not only in those cases where the mother suffered from pronounced obesity but also in cases where the women were moderately overweight. Expectant mothers who were already overweight and moreover gained a considerable amount of weight during the course of the pregnancy ran a greater risk of having a child who would later show signs of ADHD than did women of normal weight who experienced the same weight gain during pregnancy.

One plausible explanation is that the risk of complications during pregnancy is greater among overweight women. The foetus can also be affected by stress hormones from the mother, or by hormones or environmental toxins that are stored in the mother’s fatty tissue.; Source: Uppsala Universitet