Pre-pregnancy weight not tied to kids' behavior

NEW YORK (Reuters Health) - Despite some evidence to the contrary, women who are overweight before pregnancy may not have kids who are more vulnerable to behavioral or intellectual problems, a new study finds.

In recent years, a few studies have found that children born to overweight women tend to have more behavioral problems, including attention-deficit hyperactivity disorder (ADHD), than their peers whose mothers were normal-weight before pregnancy.

There is also some evidence linking mothers’ excess pounds to mild learning problems in their children.

But in the new study of about 7,500 British and Dutch children researchers saw no consistent correlation between mothers’ pre-pregnancy weight and their children’s intellectual development or risk of ADHD and other behavioral problems.

Instead, any links appeared to be largely explained by other factors -- like the fact that heavier mothers tended to have less education and lower incomes than normal-weight moms.

The findings suggest that mothers’ extra pounds do not directly affect fetal development in a way that harms children’s later cognitive skills or behavior, the researchers report in the journal Pediatrics.

There are still plenty of reasons for women to go into pregnancy at a healthy weight, however.

Overweight and obese women are at elevated risk of pregnancy complications like gestational (pregnancy-related) diabetes and pre-eclampsia -- a potentially dangerous disorder marked by a sudden increase in blood pressure and protein in the urine. They are also more likely to need an emergency cesarean section or have a larger-than-normal baby than women who are normal-weight before pregnancy.

Because of those concerns, experts generally recommend that women try to shed excess pounds before becoming pregnant.

If that’s not possible, heavier women are advised to gain fewer pounds during pregnancy. Current guidelines from the Institute of Medicine suggest that overweight women gain 15 to 25 pounds, and obese women 11 to 20 pounds, versus a range of 25 to 35 pounds for women who are normal-weight going into pregnancy.

For the current study, researchers led by Marie-Jo Brion, of the University of Bristol in the UK, analyzed data from two larger studies on child health and development.

One followed a group of UK children born in 1991 or 1992, while the other included Dutch children born between 2002 and 2006.

Overall, Brion’s team found no clear connection between mothers’ self-reported pre-pregnancy weights and their children’s performance on tests of language and other skills at either preschool or school age.

At first glance, there appeared to be some links. Children born to overweight women tended to have lower scores on language tests, for example. But once the researchers factored in things like parents’ education and family income, the relationship no longer held.

Nor was there a consistent link between moms’ weight and children’s behavioral problems, which were rated by mothers and, in the UK study, by teachers.

The bottom line, according to Brion’s team, is that the findings do not support a biological effect of mothers’ weight itself.

SOURCE: Pediatrics, online December 27, 2010.