If your child is six months old, you should consider talking to your doctor if your child exhibits the following behavior:

  •  Doesn't reach for things
  •  Show no affection for caregivers
  •  Doesn't respond to sounds around her/him
  •  Doesn't make vowel sounds (eh, ah, oh)
  •  Doesn't laugh or squeal
  •  Seems unusually stiff or unusually floppy

If your child is nine months old, you should consider talking to your doctor if your child exhibits the following behavior:

  •  Doesn't look where you point
  •  Doesn't respond to his/her own name
  •  Doesn't babble (mama, dada)
  •  Doesn't play back and forth type games
  •  Doesn't seem to recognize familiar people

If your child is one year old, You should consider talking to your doctor if your child exhibits the following behavior:

  •  Doesn't point to things
  •  Doesn't learn gestures like waving bye bye, or shaking head yes or no
  •  Doesn't search for things that she sees you hide
  •  Doesn't say single words like mama, dada, up, bye, this, that, juice
  •  Doesn't crawl
  •  Loses skills he/she once had

If your child is 18 months old, you should consider talking to your doctor if your child exhibits the following behavior:

  •  Doesn't point to show things to others
  •  Doesn't know what familiar things (cup, spoon, phone) are used for
  •  Doesn't imitate or copy others
  •  Doesn't have at least six words
  •  Doesn't gain new words
  •  Doesn't notice or react when a caregiver leaves or returns
  •  Doesn't walk
  •  Loses skills he/she once had

If your child is 2 years, you should consider talking to your doctor if your child exhibits the following behavior:

  •  Doesn't use 2-word phrases (mama up, want milk)
  •  Doesn't know what familiar things (cup, spoon, phone) are used for
  •  Doesn't imitate actions and words
  •  Doesn't follow simple instructions
  •  Doesn't walk steadily
  •  Loses skills he/she once had

If your child is 3 years old, you should consider talking to your doctor if your child exhibits the following behavior:

  •  Has unclear speech or drools a lot
  •  Doesn't speak in sentences
  •  Doesn't follow simple instructions
  •  Can't work simple toys (simple puzzles, turning knobs/handles, peg board)
  •  Shows little interest in toys
  •  Doesn't want to play with other children
  •  Doesn't play make believe or pretend
  •  Doesn't make eye contact
  •  Falls down often or has trouble on stairs
  •  Loses skills he/she once had

If your child is 4 years old, you should consider talking to your doctor if your child exhibits the following behavior:

  •  Ignores other children
  •  Doesn't respond to people outside the family
  •  Shows no interest in make believe or pretending games
  •  Can't retell a favorite story
  •  Doesn't follow 3-step directions
  •  Doesn't use "you" and "me" correctly
  •  Doesn't understand "same" and "different"
  •  Speaks unclearly
  •  Doesn't scribble or has trouble scribbling with a crayon
  •  Loses skills he/she once had

If your child is 5 years old, you should consider talking to your doctor if your child exhibits the following behavior:

  •  Doesn't show a wide range of emotions
  •  Shows behavioral extremes (unusually aggressive, fearful, sad, shy)
  •  Is unusually withdrawn and not active in social situations
  •  Is easily distracted and has trouble focusing on an activity for more than five minutes
  •  Doesn't respond to people or responds only superficially
  •  Can't tell the difference between real and make believe
  •  Doesn't participate in a wide variety of games and activities
  •  Can't give his/her first and last name
  •  Doesn't use plurals, pronouns or past tense properly
  •  Doesn't talk about daily activities
  •  Doesn't draw pictures
  •  Loses skills he/she once had