What to watch, and what to have checked
'Some children just talk late' and 'early intervention has a window' are both true. The difficulty is telling which one applies to the child in front of you. This separates normal variation from the signals worth acting on.
Updated 19 September 20265 min read
One rule overrides all the others: regression
Of every signal in this article, exactly one requires no weighing up against age and no waiting: the loss of a skill the child already had.
Words they used to say and no longer say. Walking they used to do and no longer do. Eye contact, smiling, waving that has stopped.
Development is cumulative and does not normally run backwards. Loss of skills can point to neurological or metabolic disease, and is one presentation of autism spectrum disorder. There is no version of this where watching a bit longer is the right call.
Late talking: vocabulary size is the wrong measure
Language varies enormously between children, and counting words alone misses the information that matters.
Three other things carry more diagnostic weight: comprehension, gesture, and imitation.
A 20-month-old with ten words who can fetch their shoes when asked, points at what they want, and copies you sweeping the floor is very probably just a late talker.
A 20-month-old with the same ten words who does not turn to their name, does not point, does not imitate, and does not follow your point needs assessing now.
The difference is that in the first case the language system is running and only output is slow. In the second, the whole social communication layer may be affected.
Also: a hearing test is always the first step, and the step most often skipped. Glue ear is common and straightforward to treat, and it measurably slows language development.
Why pointing carries so much weight
Parents are often puzzled by how much clinicians care about whether a child points.
There are two kinds. One means 'I want that' — imperative pointing — and most children do it. The other means 'look at that' — declarative pointing — where a child points at a dog and then looks back at you to check that you saw it too.
That second kind is the clearest expression of joint attention: the child understands that you have your own separate attention, and wants to share something with you. It is the foundation of social communication and a precondition for language, because words are learned inside shared attention.
Not pointing, not following someone else's point, and not bringing things to show you, together at 12-18 months, is a heavily weighted cluster in autism screening.
M-CHAT screening is commonly done at 18 and 24 months. If it has not been done, you can ask for it.
The list, by age
These are not standards a child must meet. They are the signals worth raising with a doctor if absent.
- 013 months: no head lift at all on the tummy; no response to sound; does not look at faces
- 026 months: no rolling; no reaching; no smiling or vocalising; uses only one side of the body
- 039 months: cannot sit unsupported; does not bring objects to the mouth; does not recognise familiar people; no consonant sounds
- 0412 months: no movement by any means; no pointing; no waving; no response to their name; no words
- 0518 months: not walking; fewer than six words; no imitation; no pointing; no eye contact
- 0624 months: fewer than 50 words; no two-word phrases; no pretend play; no interest in other children
- 0736 months: speech unintelligible to strangers; no complete sentences; cannot run; no peer interaction
- 08Any age: loss of skills; unusually floppy or stiff; persistent one-sided use of limbs; frequent falls or abnormal gait
The cost of waiting is not symmetrical
Most hesitation comes from worrying about being an over-anxious parent. But the two possible errors do not cost the same.
If you get it checked and everything is fine, the cost is an appointment, half a day, and a documented reassurance.
If it needed checking and you waited, what is lost is the intervention window. Neural plasticity is highest early in life, and intervention for language, motor and social development all work better the earlier they start. Outcomes from intervention before age three are consistently better than after, across the range of developmental conditions.
So on this particular question, err towards the extra trip. The assessment itself does no harm. The waiting can.
Who to see
The usual first stop is a child health or community paediatric service. Routine check-ups already include developmental screening instruments such as the Denver Developmental Screening Test or the Ages and Stages Questionnaire.
For suspected language problems, do a hearing test first, then consider a speech and language assessment.
For suspected social communication problems, ask about M-CHAT screening, with referral for a fuller diagnostic assessment if it is positive.
For motor development, paediatric rehabilitation or paediatric neurology.
One thing to do before you go: write down the specific behaviours you have observed, and bring video. 'He does not seem to respond to people' is far less useful than 'called his name five times, he turned once; at the playground he did not look at the other children'. A clinician has fifteen minutes in the room. Your observations are the most valuable thing you bring.
This is general reference material. It does not replace advice from your doctor. Sources: WHO Child Growth Standards, China Dietary Guidelines (2022), China National Immunization Program schedule (2021), CDC developmental milestones.
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