Mothers' pre-pregnancy weight tied to kids' IQ, study says

December 12, 2012 by Amy Norton, Healthday Reporter
Mothers' pre-pregnancy weight tied to kids' IQ, study says
Excess pounds before pregnancy may contribute to lower test scores for child.

(HealthDay)—Children whose mothers went into pregnancy overweight may have slightly lower scores on certain tests of verbal and numbers skills, a new study says.

The findings, reported online Dec. 10 in the journal Pediatrics, do not prove that their mothers' extra pounds are the reason for these decreased scores, and experts not involved in the study said it's too soon to suggest mothers-to-be lose weight for the sake of their kids' mental prowess.

But the results do add to studies showing that, for whatever reason, kids born to heavy mothers tend to have a somewhat lower IQ than their peers.

For the study, researchers led by Emre Basatemur, of the Institute of Child
Health at University College London, combed data on nearly 20,000 U.K. children involved in an ongoing national study. The children took standard tests of verbal ability, numbers skills and reasoning at the age of 5, and again at age 7.

In general, children scored slightly lower if their mother was going into pregnancy. The difference was very small, though: For every 10-point increase in mothers' body-mass indexes (BMI)—an extra 60 pounds for an average-height woman—kids' test scores dipped slightly. is a measurement of based on height and weight.

That dip in was roughly equal to a 1.5-point decline in IQ.

Exactly what difference that could make in real life is unclear, said researchers not involved in the work. What's more, there is no way to know whether mothers' extra weight is to blame.

Basatemur acknowledged that many factors, both genetic and environmental, influence children's . "The association observed in our study accounts for a small amount of the overall variation seen in children's cognition," he said.

Other experts emphasized that the study found only an association. " like this can never prove cause-and-effect," said Dr. Ryan Van Lieshout, assistant professor of psychiatry and behavioral neurosciences at McMaster University in Hamilton, Ontario.

The researchers did try to account for other factors, such as family income and parents' education. But they lacked some key information—including parents' IQ scores, said Van Lieshout, who has studied the relationship between mothers' weight and kids' development.

"You can't conclude from this that women should try to attain a healthy weight before pregnancy in order to improve their child's cognition," Van Lieshout said.

A child behavior specialist agreed. One question is what mothers' nutrition was like during pregnancy, said Andrea Vazzana, clinical assistant professor of child and adolescent psychiatry at NYU Langone Medical Center in New York City.

Since nutrition during pregnancy affects fetal development, it's possible that differences in diet—rather than weight, per se—have some role in the findings.

But there were also problems in how the study assessed kids' abilities, Vazzana said. Their verbal, reasoning and numbers skills were each gauged with one test, or "scale." And that's not enough to broadly capture children's abilities, she said.

There also was a lot of missing data, she pointed out. For instance, the researchers had full information for only about half of the children at age 7.

Still, Van Lieshout said that nine studies so far have looked at the relationship between mothers' weight and children's mental and behavioral development, and most suggest a link.

The question, though, is why. Van Lieshout said the "most tantalizing" theory is that there could be something about mothers' excess fat that affects fetal brain development. Animal research has suggested that's possible, but no one knows if that's true in humans.

For now, the experts said, there are plenty of reasons for women to go into pregnancy as healthy as possible—which includes being neither substantially overweight nor underweight.

Basatemur said his study results should be interpreted alongside existing weight recommendations. "The association observed in our study may be a further reason to follow this advice, and reinforce the need ... to reduce the prevalence of overweight and obesity in women of childbearing age," he said.

Obesity can make it more difficult to get pregnant, and it raises the odds of certain health problems for expectant , such as pregnancy-related diabetes and high blood pressure. Obesity also has been linked to higher-than-normal risks of miscarriage, stillbirth and birth defects.

Van Lieshout agreed that "there are absolutely reasons" to strive for a healthy weight before pregnancy. "We just don't know if this is one of them," he said.

Explore further: Excess weight in pregnant women can have negative implications for offspring

More information: Learn more about having a healthy pregnancy from the U.S. Centers for Disease Control and Prevention.

Related Stories

Excess weight in pregnant women can have negative implications for offspring

May 14, 2012
That overweight during pregnancy can lead to overweight children and adolescents has been known for some time, but new research at the Hebrew University of Jerusalem and in the US indicates that excess weight before and during ...

Mothers, children underestimate obesity in China

August 6, 2012
Childhood obesity is on the rise in China, and children and parents there tend to underestimate body weight, according to Penn State health policy researchers.

Study shows link between pre-pregnancy obesity and lower test scores

May 8, 2012
Women who are obese before they become pregnant are at higher risk of having children with lower cognitive function - as measured by math and reading tests taken between ages 5 to 7 years - than are mothers with a healthy ...

Recommended for you

Who uses phone apps to track sleep habits? Mostly the healthy and wealthy in US

January 16, 2018
The profile of most Americans who use popular mobile phone apps that track sleep habits is that they are relatively affluent, claim to eat well, and say they are in good health, even if some of them tend to smoke.

Improvements in mortality rates are slowed by rise in obesity in the United States

January 15, 2018
With countless medical advances and efforts to curb smoking, one might expect that life expectancy in the United States would improve. Yet according to recent studies, there's been a reduction in the rate of improvement in ...

Teens likely to crave junk food after watching TV ads

January 15, 2018
Teenagers who watch more than three hours of commercial TV a day are more likely to eat hundreds of extra junk food snacks, according to a report by Cancer Research UK.

Can muesli help against arthritis?

January 15, 2018
It is well known that healthy eating increases a general sense of wellbeing. Researchers at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have now discovered that a fibre-rich diet can have a positive influence ...

Your dishwasher is not as sterile as you think

January 13, 2018
(HealthDay)—Your dishwasher may get those plates spotless, but it is also probably teeming with bacteria and fungus, a new study suggests.

Study reveals what sleep talkers have to say

January 12, 2018
A team of researchers with members from several institutions in France has conducted a study regarding sleep talking and has found that most sleep talking is not only negative in nature, but involves a large amount of swearing. ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.