Typical and Atypical Development
Framing development
Typical development is assessed across separate but linked domains: growth, gross and fine motor, language, cognitive, social-emotional, and regulatory (sleep, feeding, temperament). Plot growth on WHO charts for 0-2 years and CDC charts for 2 years and older; length, weight, and head circumference should track together. A child who crosses two major centiles, or whose head circumference diverges, needs evaluation rather than reassurance.
Milestone anchors
Head control by 3-4 months, sitting without support by 6-8 months, and independent walking by 12-15 months (up to 18 months) are common anchors. Language: cooing by 2 months, canonical babbling by 6 months, first words around 12 months, 50 words and two-word combinations by 18-24 months. Social smile by 6-8 weeks, stranger anxiety by 6-9 months, and parallel play in toddlers are expected. Use corrected age for infants born preterm until 24 months.
Traps
Questions often minimize delay because a child is bilingual, male, or “shy”; bilingual children should meet milestones in the dominant language. Isolated delay differs from global delay. Regression at any age is abnormal. Asymmetry, persistent primitive reflexes, or hand fisting suggest cerebral palsy. Do not accept “he will outgrow it” when two domains are delayed.
Worked example
An 18-month-old born at 28 weeks is not walking but bangs blocks and says three words. Corrected age is about 16 months, so walking is still within range; language is borderline. The rule of thumb: correct for prematurity, but refer for early intervention when any domain is significantly delayed or when there is concern about regression.