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WHO Length-for-Age Growth Chart (0-24 Months)

Plot your child's recumbent length against WHO growth standards for ages 0-24 months. The chart displays standard percentile curves with your child's measurement highlighted.

LMS Method: Z = ((X/M)^L - 1) / (L x S)

How It Works

This calculator uses WHO growth standards for monitoring recumbent length in children from birth to 24 months. Length-for-age is a key indicator of chronic nutritional status and overall health. The WHO standards are based on healthy breastfed children from six countries under optimal conditions. The LMS method computes Z-scores and percentiles using daily LMS data for precise age matching.

Example Problem

A 12-month-old boy has a recumbent length of 75.7 cm. What is his length-for-age percentile?

  1. Enter the child's date of birth and measurement date (12 months apart).
  2. Select 'Boy' for gender.
  3. Enter 75.7 cm for length.
  4. The calculator finds the LMS parameters for boys at 12 months and computes the Z-score.
  5. Result: approximately the 50th percentile, as 75.7 cm is near the WHO median length for boys at 12 months.

Key Concepts

Length-for-age reflects chronic nutritional status and overall health. Recumbent length is measured lying down and is standard for children under 24 months. Standing height is about 0.7 cm shorter than recumbent length. A shift of one percentile band is common and usually normal, but crossing two or more major percentile lines warrants discussion with your pediatrician. For premature infants, use corrected age until about 24 months.

Applications

  • Routine growth monitoring at well-child visits
  • Assessing chronic nutritional status in infants
  • Identifying potential stunting or growth disorders
  • Tracking catch-up growth in premature infants using corrected age
  • Comparing growth across international populations

Common Mistakes

  • Measuring standing height instead of recumbent length for children under 2 — recumbent length is about 0.7 cm longer
  • Not using corrected age for premature infants during the first 2 years
  • Confusing WHO standards with CDC charts — WHO describes optimal growth, CDC describes U.S. population growth
  • Worrying about a single measurement crossing percentile lines — trends over multiple visits matter more
  • Inaccurate home measurements — clinical measurements with a proper infantometer are much more reliable

Frequently Asked Questions

What is the difference between length and height?

Length is measured with the child lying down (recumbent) and is standard for children under 24 months. Height is measured standing up. Recumbent length is typically about 0.7 cm longer than standing height.

My child dropped percentiles. Should I be worried?

A shift of one percentile band is common and usually normal. Crossing two or more major percentile lines (for example, from the 75th to the 25th) warrants a conversation with your pediatrician to rule out nutritional or medical issues.

Do premature babies use the same chart?

For premature infants, pediatricians typically use corrected age (age from the due date, not birth date) until about 24 months. Enter the corrected dates to get a more appropriate comparison.

Are the WHO standards the same as CDC growth charts?

No. The CDC recommends using WHO growth standards for children under 2 years and CDC growth charts for ages 2-20. The WHO standards are based on how healthy breastfed children should grow, while CDC charts describe how children in the US actually grew during a specific time period.

Reference: WHO Child Growth Standards. World Health Organization, 2006. https://www.who.int/tools/child-growth-standards

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