Worried Your Child May Have Autism? A Closer Look at Early Signs and Screening Guidelines

Recent data show that the number of children with autism spectrum disorder (ASD) is growing. A report released in April 2025 notes that 1 out of every 31 children is affected in some way with ASD. Early treatment yields the most optimal results. 

Board-certified pediatric neurologist, Dr. Charles Niesen, and our team at AMS Neurology in Pasadena, California, diagnose and treat children with autism spectrum disorder so they thrive and are better able to live up to their potential. 

Babies and children with ASD have differences in social and communication skills and may exhibit repetitive or rigid behaviors. 

If you have an older child, you have an idea of how a baby progresses through developmental stages. If this is your first child, however, you may not be sure what your loved one should be able to do at six or nine months, or one year. 

Early signs of autism 

The following is a helpful guide to the early signs of autism. If your baby or toddler shows any of these signs, it’s important to follow up with a pediatric neurologist. 

6 months

Does your little one give you a big smile when you play with them? Do they give you a big belly laugh when you do something silly? If your baby isn’t smiling at you or responding positively when you show attention and play with them, call our office for an appointment. 

9 months 

By around nine months, most babies begin to display a range of facial expressions. Many also respond to simple social games such as peek‑a‑boo by smiling, laughing, or covering their face. 

If your child isn’t showing a range of facial expressions, such as happiness, sadness, anger, or surprise, by around nine months, it’s a good idea to talk with your pediatrician to see whether a developmental or neurological evaluation is needed. There should be a back-and-forth reciprocal sharing of expressions and sounds as you talk to them.

12 months

Does your baby turn their head when you call their name? Your child should also be using some arm and hand gestures by the time they’re a year old. If you’ve been practicing waving goodbye, many babies will start to imitate the gesture when you say something like, “let’s say goodbye.” 

18 months

Does your child point to something funny or something they like? They should be engaging in reciprocal behaviors at this point. 

24 months 

By the time your toddler is two years old, they should be speaking in two-word sentences, such as “dog run” or “baby cry.” Some children can use phrases or simple sentences. 

Differences in behavior start to become noticeable at this age. Many babies flap their hands when excited. However, if your baby flaps their hands repeatedly, begins spinning in circles, or rocks constantly, they should be seen by a specialist. 

36 months

Your child should be enjoying parallel play with other toddlers, playing alongside others, watching, and sometimes doing what the other children do. This phase bridges independent play with cooperative play and occurs around age four. 

If your child doesn’t seem to notice or have an interest in other children, please call our office for an appointment. If your child consistently plays with a toy in only one very specific way or seems unusually fixated on a single type of play, it’s something worth noting and mentioning to their pediatrician. 

In terms of speech, if they constantly repeat words or phrases and don't exhibit normal speech patterns, they should be screened by a specialist. 

Screening guidelines for autism

Experts at the American Academy of Pediatrics recommend that all babies be screened for autism spectrum disorder at 18-24 months of age. 

Your child’s primary care provider uses a screening tool called the Modified Checklist for Autism in Toddlers, which you, the parent, complete by answering questions about your baby’s behaviors. If your primary care provider has concerns when you bring your child in for appointments, they’ll refer you to a specialist.

Research shows that the earlier children are diagnosed with autism spectrum disorder, the better the outcome. Call AMS Neurology or book an appointment online today if your child's development isn’t in alignment with normal milestones.