Developmental Red Flags: When to See a Doctor

Most children develop at their own pace, and being a little early or late on a milestone is usually nothing to worry about. But some signs deserve attention sooner rather than later. This guide lists red flags by age — things that suggest your child may need professional support. It is not a checklist for diagnosis.

Important: This page is educational and for self-reflection only. It is not a diagnostic tool. If your child shows any of these signs, or you simply feel something is not right, talk with your child's doctor and ask about developmental screening. Acting early gives children the best chance to catch up.

The Most Important Rule: Trust Your Instincts

You know your child best. You do not need a list to confirm a worry. If you are concerned about how your child plays, learns, speaks, acts, or moves — don't wait. Share your concerns with your child's doctor even if a well-child visit is not due yet.

Red Flags by Age

These lists follow the CDC "Learn the Signs. Act Early." checkpoints. Each item is a sign to talk with your doctor about, not a diagnosis.

By 2 Months

  • Does not respond to loud sounds
  • Does not watch things as they move
  • Does not smile at people
  • Cannot hold their head up when lying on their tummy and pushing up

By 4 Months

  • Does not watch things as they move
  • Does not smile at people
  • Cannot hold their head steady
  • Does not coo or make sounds
  • Does not bring things to their mouth
  • Does not push down with their legs when their feet are placed on a hard surface

By 6 Months

  • Does not try to get things that are in reach
  • Does not show affection to caregivers
  • Does not respond to sounds around them
  • Does not roll over in either direction
  • Laughs or squeals very rarely
  • Seems unusually stiff or unusually floppy, or is hard to calm down

By 9 Months

  • Does not sit with help
  • Does not respond to their own name
  • Does not smile back when others smile at them
  • Does not babble "mama," "baba," or "dada"
  • Does not play games like peek-a-boo

By 12 Months

  • Does not crawl
  • Cannot stand when supported
  • Does not say single words like "mama" or "dada"
  • Does not point to things
  • Loses skills they once had

By 18 Months

  • Does not point to show things to others
  • Does not walk
  • Does not know what familiar things are for (brush, phone, spoon)
  • Does not copy others
  • Does not gain new words
  • Loses skills they once had

By 2 Years (24 Months)

  • Does not use two-word phrases like "more milk"
  • Does not know what to do with common things (brush, phone, spoon)
  • Does not copy actions and words
  • Does not follow simple instructions
  • Loses skills they once had

By 3 Years (36 Months)

  • Falls a lot or has trouble going up and down stairs
  • Drools or has very unclear speech
  • Does not speak in sentences
  • Does not understand simple instructions
  • Does not play pretend or make-believe
  • Does not want to play with other children
  • Does not make eye contact
  • Loses skills they once had

By 4 Years (48 Months)

  • Cannot jump in place
  • Has trouble scribbling
  • Does not follow three-part instructions
  • Does not understand "same" and "different"
  • Does not use "me" and "you" correctly
  • Speaks unclearly (unfamiliar listeners cannot understand)
  • Loses skills they once had

By 5 Years (60 Months)

  • Does not show a wide range of emotions
  • Shows extreme behavior: unusually fearful, aggressive, shy, or sad
  • Is withdrawn or not active
  • Is easily distracted, or cannot focus on one activity for more than about 5 minutes
  • Does not respond to people, or responds only superficially
  • Cannot tell what is real and what is make-believe
  • Does not play a variety of games and activities
  • Cannot give their first and last name
  • Does not use plurals or past tense properly
  • Does not talk about daily activities or experiences
  • Does not draw pictures
  • Loses skills they once had

Losing Skills Is Always a Red Flag

At any age, a child who loses skills they once had — stops talking, stops walking, stops responding, stops playing — should be seen by a doctor promptly. Skill regression can be an early sign of conditions that respond best to early treatment.

Where to Seek Help

Start with your child's doctor. Share your specific concerns and ask about:

  • Developmental screening — a short, validated questionnaire or check-up that looks at how your child plays, learns, speaks, acts, and moves. In many places this is routine at well-child visits; ask if it has been done.
  • A referral to a specialist if concerns continue. Depending on the concern, this may be a developmental-behavioral pediatrician, child neurologist, audiologist, speech-language pathologist, occupational or physical therapist, or child psychologist.
  • Early intervention services — in the U.S., state early intervention programs provide free evaluations and services for young children (often birth to age 3). In China, you can contact your local 儿童保健门诊 (child health clinic), 发育行为儿科 (developmental-behavioral pediatrics), or rehabilitation departments.

Don't "wait and see." Research consistently shows that children who receive support earlier make faster progress. A worry you raise today — even if it turns out to be nothing — is always worth raising.

Related Reading

References

Last updated: 2026-10-20

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