Normal Development and Growth
What to know
Development is assessed along four streams - gross motor, fine motor/vision, language, and social/adaptive - and the examiner should track trajectory rather than isolated points. Typical timing: head control 3–4 months, sitting without support 6–8 months, pulling to stand 9–10 months, independent walking 12–15 months (18 months is the outer limit), pincer grasp 9–12 months, first word at 12 months, 50-word vocabulary and two-word combinations by 24 months, three-word sentences and strangers understanding most speech by 3–4 years. Primitive reflexes (Moro, palmar grasp, asymmetric tonic neck) should disappear by 4–6 months; persistence signals a central motor problem.
Growth uses WHO charts below 2 years and CDC above; preterm infants are plotted by corrected age until 2–2.5 years. Head circumference is the single most useful screen - crossing two major percentile lines downward, or a value above the 97th or below the 3rd percentile, warrants imaging or at least close follow-up.
Traps
Questions love normal variants: benign hypotonia, asymmetric crawl, toe-walking, and language delay in a bilingual home. Conversely, three findings are never normal - loss of previously acquired skills, hand preference before 18 months (suggests hemiparesis), and persistent asymmetry of movement or tone.
Worked rule
A 17-month-old not yet walking with a normal neurologic exam: observe and reassess in 4–8 weeks. At 18 months without walking, begin evaluation (CK, hip films, developmental referral). Failure of language at 16 months, or no two-word phrases at 24 months, triggers audiology and speech evaluation regardless of motor status.