25 November 2001

Stress During Pregnancy Linked To Autism

by Kate Melville

Women who have had a major stressful event - death of a spouse, job loss, or a long-distance move - midway through their pregnancy may have a greater chance of having an autistic child than do their unstressed counterparts say researchers at Ohio State University Medical Center.

In a presentation at the annual meeting of the Society for Neuroscience in San Diego, Dr. David Beversdorf, a neurologist at OSU Medical Center and principal investigator of the study, reported on a study of 188 women who had delivered autistic children. The research showed that these women were more likely to have experienced a major stressor the 24th through 28th weeks of their pregnancy.

"Researchers have been examining the genetic component of the disease for years, but there is now evidence through this study that autism is also linked to external factors, such as prenatal stress," he said.

Beversdorf and his collegues asked mothers to document their stress levels when stressful events occurred during their pregnancies. The study included the mothers of autistic children, 212 women who had normal births and 92 women who had children with Down's syndrome - a genetically caused neurological disorder caused by chromosomal abnormality.

The researchers then used a standard psychological measure - The Social Readjustment Rating Scale - to gauge the impact at four-week intervals that those stressors had on the women.

For the study, a "major stressor" was defined as a life-altering event in the woman's life, such a loss of a loved one or losing a job.

He noted that the numbers of women experiencing major stress during any certain four-week period in their pregnancies remained fairly constant during the study for normal and Down's syndrome pregnancies. Stress levels for the mothers of autistic children were nearly twice those of other mothers in the study.

"We expected that a woman who has had an autistic child or a child with Down's syndrome would tend to remember these life stressors more easily than a woman who has had a normal birth," he said.

"What we were looking for was this rise in the numbers of who had a major stressor during this time period (before 32 weeks) and that these women also had autistic children."

Beversdorf and his colleagues believe their research supports earlier animal studies that suggest stress during specific periods in the pregnancy may lead to structural changes in the brain that have been linked to autism.

The timing of the stressful events recorded for the study seem to mesh well, timewise, with the periods of development of the fetal cerebellum - a key portion of the brain that is structurally different in autistic children.

Autism is a neurological disorder that tends to appear early in a child's life, typically before age 3. These children have problems interacting and communicating with others, have a language delay, and develop a narrow and repetitive pattern of behaviors. These behaviors typically stay with the child throughout his or her life.

"With this information there will be other studies that can hopefully determine what are the causes and influences of autism in children," said Beversdorf.