• Doesn’t make eye contact (e.g. look at you when being fed)
• Doesn't smile when smiled at
• Doesn't respond to his or her name or to the sound of a familiar voice
• Doesn't point or wave goodbye or use other gestures to communicate
• Doesn’t follow the gesture when you point things out
• Doesn’t make noises to get your attention
• Doesn’t initiate or respond to cuddling
• Doesn’t imitate your movements and facial expressions
• Doesn’t play with other people or share interest and enjoyment
• Doesn’t ask for help or make other basic requests

• By 6 months: No big smiles or other warm, joyful expressions
• By 9 months: No back-and-forth sharing of sounds, smiles, or other facial expressions
• By 12 months: Lack of response to name.
• By 12 months: No babbling or “baby talk.”
• By 12 months: No back-and-forth gestures, such as pointing, showing, reaching, or waving.
• By 16 months: No spoken words.
• By 24 months: No meaningful two-word phrases that don’t involve imitating or repeating.

Basic social interaction can be difficult for children with autism spectrum disorders. Many kids on the autism spectrum seem to prefer to live in their own world, aloof and detached from others.

• Appears disinterested or unaware of other people or what’s going on around them.
• Doesn’t know how to connect with others, play, or make friends
• Prefers not to be touched, held, or cuddled
• Doesn’t play "pretend" games, engage in group games, imitate others, or use toys in creative ways
• Has trouble understanding or talking about feelings
• Doesn’t seem to hear when others talk to him or her
• Doesn't share interests or achievements with others (drawings, toys).

Children with autism spectrum disorders have difficulty with speech and language. Often, they start talking late.

• Speaks in an abnormal tone of voice, or with an odd rhythm or pitch (e.g. ends every sentence as if asking a question).
• Repeats the same words or phrases over and over
• Responds to a question by repeating it, rather than answering it
• Refers to themselves in the third person.
• Uses language incorrectly (grammatical errors, wrong words).
• Has difficulty communicating needs or desires
• Doesn’t understand simple directions, statements, or questions.
• Takes what is said too literally (misses undertones of humor, irony, and sarcasm).

Children with autism spectrum disorders have trouble picking up on subtle nonverbal cues and using body language. This makes the "give-and-take" of social interaction very difficult.

• Avoids eye contact
• Uses facial expressions that don't match what he or she is saying
• Doesn’t pick up on other people’s facial expressions, tone of voice, and gestures.
• Makes very few gestures (such as pointing). May come across as cold or “robot-like.”
• Reacts unusually to sights, smells, textures, and sounds. May be especially sensitive to loud noises.
• Abnormal posture, clumsiness, or eccentric ways of moving (e.g. walking exclusively on tiptoe).

Children with autism spectrum disorders are often restricted, inflexible, and even obsessive in their behaviors, activities, and interests.

• Follows a rigid routine (e.g. insists on taking a specific route to school)
• Has difficulty adapting to any changes in schedule or environment (e.g. throws a tantrum if the furniture is rearranged or bedtime is at a different time than usual).
• Unusual attachments to toys or strange objects such as keys, light switches, or rubber bands.
• Obsessively lines things up or arranges them in a certain order.
• Preoccupation with a narrow topic of interest, often involving numbers or symbols (e.g. memorizing and reciting facts about maps, train schedules, or sports statistics).
• Spends long periods of time arranging toys in specific ways, watching moving objects such as a ceiling fan, or focusing on one specific part of an object such as the wheels of a toy car.
• Repeats the same actions or movements over and over again, such as flapping hands, rocking, or twirling (known as self-stimulatory behavior, or “stimming”). Some researchers and clinicians believe that these behaviors may soothe children with autism more than stimulate them.

• Hand flapping
• Rocking back and forth
• Spinning in a circle
• Finger flicking
• Head banging
• Staring at lights
• Moving fingers in front of the eyes
• Snapping fingers
• Tapping ears
• Scratching
• Lining up toys
• Spinning objects
• Wheel spinning
• Watching moving objects
• Flicking light switches on and off
• Repeating words or noises

Until recently, most scientists believed that autism is caused mostly by genetic factors. But groundbreaking new research indicates that environmental factors may be just as important in the development of autism—if not more so—than genes. It appears that certain babies are born with a genetic vulnerability to autism that is then triggered by something in the external environment, either while he or she is still in the womb or sometime after birth. It’s important to note that the environment, in this context, means anything outside the body. It’s not limited to things like pollution or toxins in the atmosphere. In fact, one of the most important environments appears to be the prenatal environment.

• Taking antidepressants during pregnancy, especially in the first 3 months
• Nutritional deficiencies early in pregnancy, particularly not getting enough folic acid
• The age of the mother (children born to older fathers also have a higher risk of autism)
• Complications at or shortly after birth, including very low birth weight and neonatal anemia
• Maternal infections during pregnancy
• Exposure to chemical pollutants, such as metals and pesticides, while pregnant While more research on these prenatal risk factors is needed, if you’re pregnant or trying to conceive, it can’t hurt to take steps now to reduce your baby’s risk of autism.