9 months
At this age, we can accurately detect problems of crucial developmental milestones, including hearing, vision, and motor development. Also at this time, we may be able to detect delay or deviate social and communication skills, such as the ability to make eye contact, form attachment with the caregiver, indicate their needs, and share their interest to their family member. The delay or deficit social interaction may be an early sign of a particular developmental disorder.
If a child cannot be assessed at 9 months, at least he/she should be assessed before 1 year old.
18 months
One and a half year old is an important stage for language development. At this age, a child should be able to say at least one single word, not including words to call out to family members such as papa, mama or dada. If any child is unable to use meaningful words at this age, he/she should be assessed for his/her receptive language (or ability to understand what other people say). A child should be able to follow some simple commands such as “bring a ball to mama”, or “put this in the bin”. If a child isn’t using any meaningful words, and is unable to understand or seems uninterested in other people, he/she should be assessed for possible developmental disorders, such as Autism or developmental language disorder, by developmental specialist.
Crucial problems on motor development should be assessed at this age. If a child has not achieved proper motor milestones such as walking, or shows regression of previous motor development, these findings could be red flags sign for serious neurological disorder.
Children with autism usually show social interaction deficit, delayed communication skills, and may show unusual or limited interest or repetitive behaviors. Well established research evidences confirm that early identification is the key to success for Autism treatment. The earlier the diagnosis is made, the sooner treatment is started, the better outcome of the child achieves.
24–30 months
At this age, any significant developmental problems related to motor, language and social development should have been identified and treatment should have been started already. However, for subtle problems or milder form of developmental disorder, they might just be recognized around this age. Therefore, it is worth to do a final full developmental assessment to pick up any concerns or late problems at this age.
Moreover, this age is the time to prepare for school readiness. In many countries, such as in Thailand, a child starts school at the age of 3, in kindergarten level. Therefore, at two years old, parents should have the opportunity to get advice, discuss about school plans with pediatrician, includes school readiness evaluation and any other concerns on a child’s behavior, especially on attention skill, self-help skill, and social skill.