WHO Growth Standards: Average Height & Weight for 21-Month-Old Girl

Per WHO Child Growth Standards (2006), the median (50th percentile) for a 21-month-old girl:

• Height: 83.8 cm (33.0 inches)
• Weight: 11.7 kg (25.8 lbs)

Important Context

• Median ≠ "ideal" – healthy range spans ~3rd–97th percentile
• Individual trajectory matters – track on WHO charts at each visit
• Feeding method affects pattern – breastfed infants leaner after 6 mo
• Clinical assessment > percentiles – pediatrician evaluates whole child

When to Discuss with Doctor

• Crossing ≥2 major percentile lines
• Weight-for-length <3rd or >97th
• Developmental concerns
• Feeding difficulties