A new provocative study shows that compared to healthy-weight mothers, obese women are 67 percent more likely to have a child with autism. They were also about twice as likely to have a child with another developmental disorder.
Can autism be preventable? Scientists say, yes. And autism research points to early diagnosis and intervention — as early as when the child is eight months old — as the best way to stop this disabling brain disorder in its tracks.
But really being able to prevent autism requires a complete understanding of its causes — and scientists are still putting together that picture, despite intensive research for many decades.
Although the exact causes of autism are not known, scientists believe genetics is responsible for over half of the risk of a child developing autism and new research suggests multiple genetic mutations make a child susceptible for the disorder. The remaining half involves factors that include older parental age, premature birth or failure to take prenatal vitamins. Exposure to chemicals and other agents that can cause birth defects have also been shown to cause autism.
In recent years, scientists have also been looking for environmental triggers that push the children who are genetically prone to autism to actually go on and exhibit the social and communication skills problems that characterize the disorder — repetitive behaviors like rocking back and forth, trouble speaking, interacting with others or socializing and making friends with peers.
As the search for these triggers continues, new research from the University of California Davis MIND (Medical Investigation of Neurodevelopmental Disorders) Institute suggests that obesity may be one of those triggers.
To be more precise, the authors of the latest research say that, compared with healthy-weight mothers, women who are obese during their pregnancies are significantly more likely to have a child with autism and other developmental disorders.
Obesity and diabetes during pregnancy may be risk factors for autism spectrum disorder (ASD) and other neurodevelopmental problems in childhood, the new study of more than 1,000 children and their mothers concludes.
The authors say it’s the first study to examine the link between neurodevelopmental disorders and maternal metabolic conditions. Their findings are published in the May issue of the journal Pediatrics.
The authors warn that the findings could have serious public-health implications, given the ever-rising worldwide rates of obesity — and obesity in women of childbearing age. The link between obesity and developmental disorders is particularly worrisome because obesity has become so prevalent:
• In the United States, nearly 60 percent of women of childbearing age (20 to 39) are overweight and one-third are obese.
• According to Statistics Canada, 29 per cent of Canadian women are overweight and 23 percent are obese.
• According to the European Commission, obesity rates have more than doubled over the past 20 years in most European Union countries and over half the EU adult population is now classified as overweight or obese. The UK has the worst obesity rate in Europe with nearly one in four adults now classified as obese.
• There are an estimated 502 million obese adults worldwide, and the obesity epidemic is sweeping into low and middle-income countries, the World Health Organization’s obesity center reported in 2011.
• Obesity rates have been climbing fastest for women 25 to 34 years old, nearly doubling in the past 25 years.
The new findings follow a recent announcement by the U.S. Centers for Disease Control and Prevention announcement that autism-spectrum disorders affect one in 88 U.S. children, up from one in 110 in a 2009 report. The findings also add to the increasingly complex picture of possible factors that contribute to the disorders.
The UC David MIND researchers started out knowing that while autism’s cause is unknown, previous research suggests that its “pathogenesis” — or the chain of events leading to the disorder — most likely begins in the womb. This prompted them to wonder if there was a link between autism and maternal metabolic disorders.
“Over a third of U.S. women in their childbearing years are obese and nearly one-tenth have gestational or type 2 diabetes during pregnancy,” Paula Krakowiak, a biostatician with the MIND Institute tells CNN Health. “Our finding that these maternal conditions may be linked with neurodevelopment problems in children raises concerns and therefore may have serious public-health implications.”
For their study, the researchers from the UC David MIND — as well as the Vanderbilt University — analyzed data from children two to five years old born in California and enrolled in the CHARGE (Childhood Autism Risks from Genetics and the Environment) Study between January 2003 and June 2010.
• The children were between 24 and 60 months old
• 517 children who had autism
• 172 with other developmental disorders
• 315 children who were developing normally — the were used as the “controls”
The investigators used telephone interviews and medical records to gather information about the mothers, such as the mother’s age at delivery, education level, health status and other factors. This is what they found:
• 21.5 percent of the mothers of autistic children — and 23.8 percent of mothers of children with another developmental disorder — were obese
• 14.3 per cent of mothers of normally developing children were obese
• Or, expressed in another way, compared to healthy-weight mothers, obese women were 67 percent more likely to have a child with autism. They were also about twice as likely to have a child with another developmental disorder.
Compared with the “control” mothers, mothers of children with autism or other developmental disorders also have diabetes and high blood pressure — aside from obesity. Excess weight increases the risk of women developing diabetes during pregnancy.