Pick up yellow block. Mouth it. Bang it. Pick up red block. Mouth, bang. Pick up blue block... For babies this age, mouthing and banging are important milestones. Babies who later develop autism engage in this sort of play, but they also manipulate toys in ways that typical-developing infants rarely do, new research from the University of California at Davis shows. Infants who are later diagnosed with autism are more likely to spin a toy, stare at it for a prolonged period, or use their peripheral vision to look at it. "We know that playing with toys like this is a symptom of autism in preschoolers," says study author Sally Ozonoff, Ph.D. "What surprised us was that we could see these behaviors at twelve months." Although this type of play doesn't necessarily indicate a problem, if your baby often looks at playthings from the side or repeatedly spins toys, tell your doctor, who can do a full evaluation.

What to watch for:

In addition to unusual play, these warning signs are worth talking to your pediatrician about your child.
œ Doesn't respond to his name.
œ Seldom makes eye contact with you.
œ Prefers to play alone. He doesn't get excited when you try to engage him with a toy or activity.