Growth, Development, and Developmental-Behavioral Assessment
This domain tests accurate plotting and interpretation of growth plus developmental surveillance, screening, and referral - distinguishing variation from pathology.
Core rules
- Use WHO charts for birth to 24 months (weight-for-length, head circumference) and CDC charts from 2 years (BMI at 2 years and older). Plot every visit; a single point is less informative than the trajectory.
- Faltering growth is suggested by crossing two or more major centile lines downward, falling below the expected curve, or poor growth velocity - not by one low normal value.
- Correct for prematurity in developmental assessment until about 2 years; use corrected age for plotting in preterm infants per local practice.
- Surveillance at every visit (parent concerns, milestones, observation) differs from screening with a validated tool such as ASQ-3 or M-CHAT-R/F.
- Red flags: loss of previously acquired skills, no social smile by 3 months, no babbling by 9 months, no pointing to show by 18 months, no two-word phrases by 24 months, persistent asymmetry, or abnormal tone.
- Referral pathways: Early Intervention (IDEA Part C) under age 3; school district from age 3; audiology for any language delay; autism evaluation for positive screening plus clinical concern.
Worked example
An 18-month-old says five words, does not point to show, does not respond consistently to his name, and has stopped using the two words he had at 15 months. Reasoning: regression and absent joint attention are red flags. Arrange audiology first, refer to Early Intervention now, and refer for a diagnostic autism evaluation; do not defer to "he'll catch up." M-CHAT-R/F is positive and supports, but does not replace, clinical judgment.
Traps
Relying on a single milestone checklist; failing to correct for prematurity; labeling a child "lazy" or "shy" instead of screening; missing regression; referring only to the school district for a 2-year-old.