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January 11, 2011

Study Links Spacing Between Pregnancies to Autism

Autism is a complex disability that affects a person’s ability to communicate with others. Researchers don’t know what causes it, but they suspect both genetic and environmental factors are involved. A new study links the risk of autism to the amount of time in between pregnancies.


Women who get pregnant soon after their first child is born increase the chances of autism for their second child - that’s according to a study from Columbia University.

The study’s authors looked at the medical records of more than half a million children who were second-born and the amount of time between a mother’s first pregnancy and the conception of her second child.  

Dr. Thomas Frazier did not take part in the study but he is an authority on autism at the Cleveland Clinic. “If the second birth occurred within 12 months of the first birth, the child who was born second was more likely to have autism,” he said.

Make that three times more likely to have autism.  For children conceived between one and two years after the birth of a first child, researchers found they were one and a quarter times more likely to be diagnosed with autism.

Researchers say the reason for the higher risk might be because a woman’s body may have lower levels of nutrients, like folate and iron, after the first birth.  Or it could be related to higher stress levels following the first pregnancy.  The report's lead author says more studies are needed to confirm the link. Dr. Frazier agrees.

“There are a ton of possibilities though, it’s such a complex environment, the uterine environment, that we really have to chase down a number of different leads now, sort of like a detective trying to figure out what it is that might have led to this effect,” he said.

Data from the US Centers for Disease Control shows that boys are more likely to have autism than girls. The CDC estimates that some form of what's called the "Autism Spectrum Disorder" may affect one in every 110 American children.