One in 166 kids born today will have autism, but some autistic children don't show signs as a baby. Many times, the child is 2 or even older before signs of the disorder are noticeable.

Little Trevor Schwarzkopf loves to swing just like any other 4-year-old. But Trevor isn't like every other little boy. He has autism.

"Trevor couldn't hold his own head up until he was 10 months old," his mother, Lin, said.

Just months after Trevor was born, his mother knew something was wrong -- she saw the signs early.

"The children just don't seem to be developing normally," Autism researcher Dr. Jennifer Elder, of University of Florida in Gainesville, said.

Elder says the younger the child, the harder the diagnosis. Early warning signs include if your 1-year-old doesn't babble or coo. And if they don't gesture by then, that's also sign. Children should say single words by 16 months and two-word phases by 24 months.

"There is another group that starts to develop normally and for some reason its like the light switch is turned off," Elder said.

That's what happened to 13-year-old David McCormac. He was 3 when his parents noticed something wrong.

"I noticed him saying certain words, and then he wouldn't say them anymore," his mother, Virginia, said.

Loss of language is one of the primary warning signs of autism. More red flags: If the child doesn't respond to their name and can't explain what they want.

"Rather than asking the parent for something, will take the parent's hand and use it like a tool to get something," Elder said.

Other signs: If your child can't follow directions, if they walk on their toes, avoid eye contact, and don't smile when smiled at.

"Go with your gut feeling," Elder said. "If they feel like something is wrong, get the help."

Children can be diagnosed as early as 6 months old, but normally autism is detected closer to 18 months of age.