What increases the risk of autism spectrum disorder (ASD)?

Joane Goodroe
Nursing Specialist

According to the Centers for Disease Control and Prevention, approximately 1 in every 110 children has an Autism Spectrum Disorder (ASD). Autism is the fastest growing developmental disability in the country; however, understanding what increases the risk of autism is still under investigation.

The Journal of Pediatrics published a study in January 2011 that said closely spaced pregnancies were associated with an increase in the odds of a second child being diagnosed with autism. The study looked at more than 660,000 second-born children in California between 1992 and 2002. The study measured the time the second child was conceived relative to the first child, and then looked at autism diagnosis of the second sibling. The study found that second children who were conceived less than 12 months after the first child's birth were three times more likely to be diagnosed with autism than children spaced further apart. Second children conceived less than two years after the first had almost twice the odds of receiving an autism diagnosis. There are many "first" children diagnosed with autism so this data represents only one study.

Another study called EARLI is a network of research sites that will enroll and follow 1,200 mothers of children with autism at the start of another pregnancy and document the newborn child’s development through three years of age. The EARLI Study will examine possible environmental risk factors for autism and study whether there is any interplay between environmental factors and genetic susceptibility.

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Autism Spectrum Disorder is a neurological disease that presents with

  1. severe and pervasive impairments in reciprocal social skills,
  2. deficits in language skills,
  3. presence of stereotypic behaviors, restricted interests or restricted activities.

It is most often seen in children < 12-15 years old, usually before age 36 months, males are more common, females have a more severe form of the disease.

Anybody can get ASD, but it is more likely to occur in boys. For every girl with ASD, there are four boys with it. One in 100 people in the world has autism, and 1 in 68 people born in the USA has autism. That's more than 3.5 million people.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.