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Developmental red flags by age: when to ask for an evaluation

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By a twin dad6 min readUpdated 2026-05-03

Specific signs by age window — from 2 months to 24 months — that the CDC, AAP, and NHS recommend discussing with your pediatrician or health visitor.

Most milestone variation is normal. A baby who walks at 14 months instead of 11 months, or says their first words at 13 months instead of 10 months, is almost certainly developing typically. But some patterns — at specific ages — are worth bringing to a pediatrician, GP, or health visitor for a closer look. Asking is always appropriate. These checks exist precisely for this reason.

Good to know

The signs listed here are drawn directly from the CDC's updated 2022 milestone checklists, NHS guidance, and AAP recommendations. They are signs to discuss with a professional, not diagnostic criteria. A developmental evaluation is a starting point for support — not a verdict.

Wide variation in typical development is real. But regression — losing a skill a baby previously had reliably — is different from slow progress, and always warrants prompt discussion with a doctor.

By 2 months: ask your doctor or health visitor if your baby

  • Doesn't calm when you pick them up and hold them
  • Doesn't look at your face
  • Doesn't react to loud sounds (startle reflex absent)
  • Doesn't watch things move in front of them
  • Doesn't smile at people (note: social smiling begins around 6–8 weeks — the 2-month check catches this)12

By 4 months: ask your doctor or health visitor if your baby

  • Doesn't watch things as they move
  • Doesn't smile at people
  • Doesn't bring hands to mouth
  • Doesn't hold head steady when upright
  • Doesn't coo or make sounds
  • Doesn't push down with legs when feet are placed on a firm surface1

Hearing concerns at this stage: by 4 months, babies should be turning their head toward voices and familiar sounds. If there's no consistent response to sound by this age, a hearing check is warranted.

By 6 months: ask your doctor or health visitor if your baby

  • Doesn't reach for things
  • Shows no affection for familiar caregivers
  • Doesn't respond to sounds
  • Doesn't make any vowel sounds ("aah", "ooh")
  • Doesn't roll in either direction
  • Seems very stiff (limbs hard to move) or very floppy12

By 9 months: ask your doctor or health visitor if your baby

  • Doesn't sit with support
  • Doesn't babble at all ("ba-ba", "da-da", consonant-vowel combinations)
  • Doesn't respond to their own name
  • Doesn't show any interest in people around them
  • Doesn't transfer objects from one hand to the other
  • Doesn't look where you point1
Good to know

The 9-month check is important for both motor development and social communication. Both domains together give a more complete picture than either alone.

By 12 months: ask your doctor or health visitor if your baby

  • Doesn't crawl or find another way to move around (rolling, scooting, etc.)
  • Can't stand when supported
  • Doesn't say single words like "mama" or "dada" in context
  • Doesn't use gestures — no pointing, waving, shaking head
  • Doesn't search for objects they saw you hide
  • Doesn't respond to their name12

By 18 months: ask your doctor or health visitor if your child

  • Isn't walking independently
  • Doesn't say at least 6–10 words
  • Doesn't point to show you things or to ask for something
  • Doesn't notice or seem to care when caregivers leave or return
  • Doesn't copy other people1

First words by 16 months is the AAP's threshold for routine discussion. Some children have a few words by 16 months and then go through a vocabulary burst after 18 months — but a child with no words at 16 months is worth discussing with a doctor, not waiting out.3

By 24 months: ask your doctor or health visitor if your child

  • Uses fewer than 50 words
  • Doesn't combine two words together ("more milk", "daddy go", "want that")
  • Doesn't follow simple two-step instructions ("pick up the cup and bring it here")
  • Doesn't show interest in other children
  • Loses skills they previously had12

Two-word phrases by 24 months is a well-established milestone. Children who aren't combining words by this age benefit from a speech and language evaluation — early support is significantly more effective than waiting.3

Hearing and vision: check early, don't wait

Hearing and vision problems can look like language or developmental delays, because they are one of the leading causes of those delays.

Hearing concerns — discuss with a doctor if your baby:

  • Doesn't startle to loud sounds by 1 month
  • Doesn't turn toward your voice by 4 months
  • Doesn't respond to sounds in any consistent way by 6 months
  • Doesn't turn to locate sounds by 9 months

Newborn hearing screening catches many (but not all) hearing issues at birth. A baby who passed the newborn screen can still develop hearing loss in the first year — acquired hearing loss from ear infections (otitis media) is common.

Vision concerns — discuss with a doctor if your baby:

  • Doesn't fix on your face by 6–8 weeks
  • Doesn't track a slow-moving object by 2 months
  • Has eyes that appear to cross or drift persistently after 3–4 months
  • Shows an unusual light reflex in photos (white or yellowish instead of red)2

Regression: always take seriously

A child who loses a skill they previously had reliably — stops babbling after babbling consistently, loses words they were using, stops making eye contact they were making — warrants prompt discussion with a doctor, regardless of age. Regression is different from slow acquisition and is not something to take a wait-and-see approach to.1

What an evaluation means

Asking for a developmental evaluation is not the same as receiving a diagnosis. Many children evaluated for developmental concerns turn out to be typically developing — they were at the slower end of normal ranges. That's a good outcome. Early intervention services exist for children who do need support, and research is consistent that support started early is more effective than support started later.3

Your pediatrician, GP, or health visitor is the right first point of contact. Frame it simply: "I have some questions about where [name] is with [motor/language/social] development — can we discuss it?" You don't need a specific diagnosis to raise a concern.

← Back to the complete guide: Baby development from 0 to 24 months

Also in this cluster: Motor milestones by age · Language development 0–12 months

Sources

  1. Centers for Disease Control and Prevention. "Developmental Milestones." CDC Learn the Signs. Act Early., 2022. https://www.cdc.gov/ncbddd/actearly/milestones/index.html
  2. NHS. "Your baby's development." NHS, 2023. https://www.nhs.uk/conditions/baby/babys-development/
  3. American Academy of Pediatrics. "Early Intervention." healthychildren.org, 2023. https://www.healthychildren.org/English/health-issues/conditions/developmental-disabilities/Pages/Early-Intervention.aspx

Footnotes

  1. Centers for Disease Control and Prevention. "Developmental Milestones." CDC Learn the Signs. Act Early., 2022. https://www.cdc.gov/ncbddd/actearly/milestones/index.html ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8

  2. NHS. "Your baby's development." NHS, 2023. https://www.nhs.uk/conditions/baby/babys-development/ ↩ ↩2 ↩3 ↩4 ↩5

  3. American Academy of Pediatrics. "Early Intervention." healthychildren.org, 2023. https://www.healthychildren.org/English/health-issues/conditions/developmental-disabilities/Pages/Early-Intervention.aspx ↩ ↩2 ↩3

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Disclaimer: This is not medical advice. PooPeeMilk shares general information to help you make sense of what you're seeing. Always consult your pediatrician with concerns, especially if your baby seems unwell.
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