If you're concerned your child has autism, and you're getting the same response Kinninger got from her pediatrician, remember doctor's visits are often short, and your child may not be displaying the worrisome behavior you've seen so often at home. Alison Singer, executive vice president of Autism Speaks, an awareness and advocacy organization, suggests videotaping your child's behavior and showing it to the doctor. "You could play it on your laptop, or even just bring in the video camera," she says.

Getting a letter of support from your child's day-care provider or preschool teacher might also help.

"Teachers are seen as other professionals, and a letter saying, 'In 20 years of teaching, this behavior is really unusual,' can go far," says Singer, who has a 10-year-old daughter with autism. If your child isn't in day care or school, even a letter from a neighbor who knows your child could help, she says.