Condition affects more than 3 million people in the U.S.

Q: How do I know if my child has autism?

A: Autism spectrum disorder, more commonly referred to as autism, is a neurodevelopmental disorder that causes problems with social communication and restricted interests or behavioral patterns.

Until recent years, autism has been considered a relatively rare condition. Today, an estimated one out of 42 boys and one in 189 girls are diagnosed with autism in the United States. Autism affects more than 3 million individuals in this country.

The most obvious sign of autism is a delay in language. Language delay is not universal in children with autism, but parents should feel comfortable asking their pediatrician about the following potential signs of an autism spectrum disorder:

No big smiles or other joyful expressions by 6 months old. No back-and-forth sharing of sounds, smiles or other facial expressions by 9 months. No babbling, pointing, showing, reaching or waving by 12 months. No words by 16 months. Any loss of speech, babbling or social skills at any age.

As the criteria for diagnosing autism have changed and there has been increased awareness of and screening for autism, we have started to realize that symptoms of autism exist on a spectrum from mild to severe. Simply: Every child is different, with different preferences and needs, and different ways to soothe and achieve success.

Always consult your child's pediatrician concerning your child's health.

For more pediatric health news parents can use, visit our blog: 700childrens.nationwidechildrens.org.

Daniel Coury, MD, is a developmental and behavioral pediatrician at Nationwide Children's Hospital.