Pediatric Growth Charts Explained

Growth charts are one of the most important tools in pediatric healthcare. At every well-child visit from birth through adolescence, your child's weight, height, and head circumference are measured and plotted on these standardized graphs. The resulting percentile curves tell a story about your child's growth trajectory, but interpreting them correctly requires understanding what they measure, how they work, and when changes actually matter.

This guide explains the four types of growth chart measurements, the differences between WHO and CDC charts, how to read percentile curves, what growth velocity reveals, and practical examples showing how pediatricians interpret common growth patterns.

What Growth Charts Measure

Pediatric growth charts track four primary measurements, each providing different information about a child's physical development. Together, they create a comprehensive picture that is far more informative than any single measurement alone.

Weight-for-Age

Weight-for-age charts compare a child's weight to other children of the same age and sex. This is the most commonly tracked measurement and the one most parents are familiar with. It is useful for monitoring overall nutritional status and detecting acute changes in health. However, weight-for-age alone does not distinguish between a child who is heavy because they are tall and one who is heavy for their height, which is why additional measurements are needed.

Length and Height-for-Age

Length is measured lying down for children under 2 years, and height is measured standing for children 2 and older. This distinction matters because standing height is typically about 0.7 cm less than recumbent length due to gravity compressing the spine. Length and height-for-age charts assess skeletal growth and are particularly sensitive to chronic nutritional deficiency and certain endocrine conditions like growth hormone deficiency or hypothyroidism. Unlike weight, which can change rapidly with illness or dietary changes, height reflects long-term growth trends.

Head Circumference-for-Age

Head circumference is measured routinely from birth through age 2 to 3 years, a period of rapid brain growth. The brain reaches approximately 80% of its adult size by age 2. Head circumference serves as a proxy for brain volume and is the primary screening tool for conditions that affect brain growth. Abnormally rapid head growth can indicate hydrocephalus, while slow growth may signal microcephaly or other developmental conditions.

BMI-for-Age

Body mass index for age is calculated from weight and height and is used for children aged 2 to 20 years. Unlike adult BMI categories that use fixed cutoffs, pediatric BMI is interpreted using age-specific and sex-specific percentiles because body composition changes normally throughout childhood and adolescence. BMI-for-age helps identify whether a child's weight is proportional to their height, making it more informative than weight alone for assessing nutritional status in older children and teenagers.

WHO Charts vs. CDC Charts

Understanding which growth chart is being used is essential for accurate interpretation. The two major chart systems differ in their development and intended use.

The practical recommendation in the United States is to use WHO charts from birth to 24 months and then switch to CDC charts from age 2 through 20 years. The transition at age 2 aligns with when feeding method differences become less impactful and the CDC charts' broader age range becomes more useful. Internationally, the WHO charts are the standard in most countries.

How to Read a Growth Chart

A growth chart has the child's age on the horizontal axis and the measurement (weight, height, or head circumference) on the vertical axis. Smooth curved lines represent selected percentile values, typically the 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, and 97th percentiles.

To plot a measurement, find the child's age on the bottom axis, trace straight up, then find the measurement value on the side axis and trace across. The point where these two lines meet is plotted on the chart. Its position relative to the nearest percentile curves tells you the child's percentile for that measurement.

Over multiple visits, the plotted points form a growth trajectory. In a healthy child, this trajectory roughly parallels the printed percentile curves. The trajectory does not need to fall exactly on a line, and minor fluctuations between visits are normal. The overall direction and consistency of the trajectory are what pediatricians evaluate.

Percentile Interpretation Reference

These categories apply most directly to BMI-for-age in children over 2. For infants under 2, weight-for-length rather than BMI is the standard proportionality measure. In all cases, a single percentile reading is less informative than the trajectory over time. A child who has always been at the 92nd percentile is evaluated differently from one who recently jumped from the 50th to the 92nd.

Growth Velocity: The Rate of Change

Growth velocity measures how fast a child is growing over a specific period, expressed as centimeters per year for height or grams per day for weight. While percentile charts show where a child stands relative to peers at a single point, growth velocity reveals whether they are keeping up with, falling behind, or exceeding the expected rate of growth.

Normal height velocity changes dramatically with age. In the first year of life, infants typically grow 23 to 27 centimeters. Growth slows to about 12 centimeters in the second year, then settles to 5 to 7 centimeters per year during the childhood years. During the pubertal growth spurt, velocity temporarily increases to 8 to 12 centimeters per year for girls and 10 to 14 centimeters per year for boys.

A declining growth velocity that causes a child to cross percentile lines downward is one of the earliest signs of growth failure and may trigger a workup for nutritional deficiency, chronic disease, or endocrine disorders. Conversely, an accelerating velocity during catch-up growth is a positive sign that a previously ill or malnourished child is recovering.

Real-World Growth Chart Examples

Example 1: Consistent 75th Percentile

Maya, whose parents are both above average height, has tracked along the 75th percentile for both weight and height since her 2-month visit. At 3 years old, her measurements are:

• Weight: 33.5 lbs (75th percentile)
• Height: 38.5 inches (77th percentile)
• BMI-for-age: 52nd percentile

Maya's chart is an example of ideal growth. Her weight and height percentiles are closely matched, her BMI falls squarely in the healthy range, and there is no significant deviation from her established curve at any point. Her pediatrician notes consistent tracking and proportional growth, which means no further evaluation is needed beyond routine well-child monitoring.

Example 2: Crossing From 50th to 25th

James weighed 8 lbs at birth and tracked along the 50th percentile for weight until about 5 months. Between 5 and 12 months, his weight gradually shifted to the 25th percentile, where it has remained stable through 18 months. His length has been at the 30th percentile consistently.

• Birth: 8.0 lbs (50th percentile weight, 50th length)
• 6 months: 16.0 lbs (35th percentile weight, 30th length)
• 12 months: 20.0 lbs (25th percentile weight, 28th length)
• 18 months: 23.0 lbs (25th percentile weight, 30th length)

James crossed one percentile band, which is a common and usually benign finding. His parents are average in stature, but James was somewhat larger at birth and is now settling toward a lower but stable trajectory. His pediatrician notes that the crossing occurred gradually, weight is proportional to length, he is eating well, meeting milestones, and his trajectory has stabilized. This pattern is consistent with normal adjustment toward his genetic growth potential and does not warrant intervention.

Example 3: Catch-Up Growth

Lila was born at 30 weeks gestation, weighing 3 lbs 2 oz. Using her adjusted age, her growth was initially plotted below the 3rd percentile. Over her first 18 months (adjusted age), she demonstrated catch-up growth:

• 3 months adjusted: 8.5 lbs (5th percentile)
• 6 months adjusted: 13.0 lbs (15th percentile)
• 12 months adjusted: 18.5 lbs (25th percentile)
• 18 months adjusted: 22.0 lbs (30th percentile)

Lila's growth chart shows upward percentile crossing, which in the context of prematurity is a positive sign of catch-up growth. Her trajectory is moving toward the growth curve expected for her genetic potential. Both her parents are near average height. Her neonatologist and pediatrician expect her to reach a stable percentile by her second birthday adjusted age. This pattern of crossing percentile lines upward from a low starting point is the expected and desired trajectory for premature infants.

Puberty and Growth Spurts

Puberty introduces the most dramatic growth velocity change since infancy. Girls typically begin their growth spurt between ages 10 and 14, reaching peak velocity about 1 to 2 years after breast development begins. Boys begin their spurt between ages 12 and 16, typically about 2 years later than girls. The average pubertal growth spurt adds about 8 to 10 inches to a girl's height and about 10 to 12 inches to a boy's height.

During the pubertal spurt, children may temporarily cross percentile lines upward on growth charts. Early-maturing children may jump to higher percentiles during the spurt but may also stop growing sooner, while late-maturing children may temporarily fall behind their peers before experiencing their spurt. By the end of puberty, most children settle near the percentile that aligns with their mid-parental height prediction.

Weight gain during puberty also accelerates. Boys gain significant lean muscle mass, while girls increase both lean mass and body fat in preparation for reproductive maturity. BMI-for-age percentiles may shift during puberty, and pediatricians interpret these changes in the context of pubertal development stage rather than in isolation.

Genetic Potential and Growth

Genetics is the single strongest determinant of a child's growth trajectory. The mid-parental height formula provides a rough estimate of genetic height potential:

The actual adult height typically falls within plus or minus 2 inches of the mid-parental height prediction. When a child's growth trajectory is consistent with their mid-parental height estimate, even if it is at a lower or higher percentile, this is reassuring. A child tracking at the 10th percentile whose parents are both short is growing as expected. A child at the 10th percentile whose parents are both tall may warrant evaluation for growth hormone deficiency or other conditions that could be suppressing their genetic potential.

Tips for Using Growth Charts Effectively

Ask your pediatrician to show you the growth chart at each visit. Seeing the plotted trajectory with your own eyes is far more informative than hearing a single percentile number. Many electronic health records generate printable growth charts that you can take home and compare over time.

Keep a personal record of your child's measurements. While your pediatrician maintains the official chart, having your own record allows you to review trends between visits and ensures continuity if you switch providers. Record the date, measurement, and percentile at each visit.

Look at all measurements together, not just weight. Weight alone can be misleading. A child at the 80th percentile for weight and the 80th for height is proportionally appropriate. The same child at the 80th for weight and the 30th for height warrants a different evaluation. The relationship between measurements is as important as the individual numbers.

Understand that growth charts are a tool, not a diagnostic instrument. An unusual percentile or a changed trajectory prompts further evaluation but does not by itself constitute a diagnosis. Growth charts flag patterns that deserve attention, and your pediatrician uses them alongside clinical examination, dietary assessment, developmental screening, and family history to form a complete picture.

Common Mistakes to Avoid

• Focusing on a single percentile number instead of the trajectory. A child at the 15th percentile who has always been there is healthy. A child who dropped from the 60th to the 15th needs evaluation. The story is in the trend, not the snapshot.
• Using the wrong chart for the child's age. Plotting an 18-month-old on CDC charts instead of WHO charts, or plotting a breastfed infant on charts developed from formula-fed populations, can produce misleading percentile readings. Confirm which chart your provider uses.
• Assuming taller or heavier is always better. Growth charts are not a competition. Higher percentiles do not indicate a healthier or better-nourished child. The goal is consistent, proportional growth along the child's individual curve, whatever percentile that may be.
• Not accounting for prematurity. Plotting a premature baby's measurements at their actual age rather than adjusted age makes them appear to have growth failure when they may be growing perfectly well for their corrected developmental stage. Always use adjusted age for premature infants until at least 24 months.
• Reacting to measurement errors. Measurement technique matters. A squirming toddler may yield a shorter length reading than their actual size. A child weighed with shoes and a heavy diaper shows artificially high weight. If a single measurement seems drastically different from the established pattern, the first step is to remeasure before assuming the trajectory has changed.

Last updated: February 23, 2026