The correlation between the mothers' body mass
index and the child's 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 experience the same
weight gain during pregnancy.
The next step for these scientists is to
study whether there is a causal connection between the mothers'
obesity and symptoms in the child and, if so, what this is due
to. One plausible explanation is that the risk of complications
during pregnancy is greater for overweight women. The fetus 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. It is also possible that both the mother's obesity
and the child's symptoms are the result of genetic factors.
"It is important that women start off
pregnancy at an optimal body weight. It has been well documented
in recent years that mothers' overweight is associated with an
increased risk for a number of complications both to herself and
to her child. Our results could be yet another problem to add to
the list. But it is not good to be extremely thin either," says Alina Rodriguez of the Uppsala University Department of
Psychology.