Seeking Answers for Autism

Autism risk may be slightly related to pregnancy weight gain

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) In looking for a cause of autism, researchers often investigate every possibility imaginable. This includes conditions that occur when a woman is pregnant.

A recent study found a very tiny increase in a child's risk for autism when a mother gained more weight during her pregnancy.

However, the difference in weight gain between the moms was very small — only about three pounds.

In addition, the increase in risk was very small — almost not existent. It's therefore not clear that pregnancy weight gain makes a big difference to children's autism risk.

It is possible there are other factors that are common for women who have children with autism and who gain a tiny bit of extra weight during pregnancy.

"Attend all prenatal appointments."

This study, led by Deborah A. Bilder, MD, of the Department of Psychiatry at the University of Utah in Salt Lake City, looked at whether a child's autism risk was affected by the mother's pre-pregnancy weight or pregnancy weight gain.

The researchers compared two sets of children for the study.

One set included 128 children with autism spectrum disorders and 10,920 children without autism who were matched by age and sex to the children with autism.

The other set included 288 children with autism and their 493 siblings who did not have an autism spectrum disorder.

The researchers found a very tiny association between the risk of autism and the weight gained by women during their pregnancies.

In the group comparisons of non-related children, the risk of a child's later autism spectrum disorder diagnosis increased by 10 percent for every five pounds a woman gained during her pregnancy with that child.

However, the average weight gained by women with children with autism was not even five pounds more than the average weight gained by women with children without autism.

The average weight gain of women who had children with autism was 33.6 pounds, compared to 31 pounds among the mothers of children without autism.

The risk for later autism diagnosis found when comparing children with autism to their siblings was an increase of 17 percent for every five pounds gained during pregnancy.

However, again, the difference between average weight gain among the moms during their different pregnancies was tiny.

The moms had gained an average of 33.3 pounds when they were pregnant with the child who was later diagnosed with autism. When pregnant with the autistic children's sibings, the moms gained an average of 30.5 pounds.

Therefore, the increased risk for the first group was considerably lower than 10 percent, and, for the second group, considerably lower than 17 percent.

The researchers also did not find any links between autism risk and a woman's weight before she became pregnant.

The researchers proposed a hypothesis that one possible contributor to autism spectrum disorder is abnormal steroid regulation in the womb, which additional weight gain might indicate.

However, the researchers did not provide additional evidence for this possibility beyond the slight weight gain findings in this study.

Women concerned about weight gain during pregnancy should discuss the official recommendations with their OB/GYN, midwife or other care provider.

This study was published October 28 in the journal Pediatrics. The research was funded by the US Centers for Disease Control and Prevention, the Utah Registry of Autism and Developmental Disabilities, the National Institute of Mental Health, the National Institute on Aging and Autism Speaks.

One author has consulted for and served on the advisory board of BioMarin Pharmaceuticals and been a consultant on Autism Speaks grants.

Another author has also served on the BioMarin Pharmaceuticals advisory board, holds a patent with Lineagen and has received past Autism Speaks grants.

A third author has also received past Autism Speaks grants. No other conflicts of interest were reported.

Review Date: 
October 27, 2013
Last Updated:
October 28, 2013