The WHO growth charts for girls from birth to 5 years track four key measurements: weight-for-age, length/height-for-age, weight-for-length/height, and head circumference-for-age. These charts are considered the international standard for monitoring how young girls grow, and they’re the recommended tool in U.S. clinical settings for children under 2. Understanding what the numbers mean, and what counts as normal variation versus a red flag, can help you make sense of what your pediatrician is tracking at each visit.
What the WHO Charts Measure
The WHO growth standards use curved lines called percentiles (or z-scores) to show how a child’s size compares to a large reference population of healthy children. The charts cover birth through age 5 and include separate curves for girls and boys because their growth patterns differ, especially in the first two years.
For girls, the four main charts are:
- Weight-for-age: tracks body weight from birth to 5 years
- Length/height-for-age: tracks how tall your daughter is relative to her age
- Weight-for-length/height: compares weight to length rather than age, useful for spotting under- or overnutrition
- Head circumference-for-age: tracks brain and skull growth from birth to 5 years
Each chart shows several percentile lines. The 50th percentile represents the median, meaning half of healthy girls fall above and half below. The outer lines (2nd and 98th percentiles) mark the boundaries where growth is considered unusually low or high.
How These Charts Were Built
Unlike older growth references that simply described how children in one country happened to grow, the WHO standards were designed to show how children should grow under ideal conditions. The data came from a study across six countries: Brazil, Ghana, India, Norway, Oman, and the United States. Children in the study were breastfed, had access to preventive and curative healthcare, lived in sanitary environments, and had mothers who did not smoke during or after pregnancy.
Because the study deliberately selected healthy children from diverse ethnic backgrounds and cultural settings, the resulting charts work as a universal benchmark. This is why the CDC recommends using WHO charts for all children under 2 in the U.S., regardless of ethnicity or feeding method. For children aged 2 to 5, many countries continue using the WHO charts, though the CDC also offers its own reference charts for that age range.
Length vs. Height: The Age-2 Switch
The WHO charts split into two segments for length and height. From birth to 2 years, your daughter is measured lying down (recumbent length). From age 2 to 5, she’s measured standing up. This matters because standing height is about 0.7 cm shorter than recumbent length, simply due to gravity compressing the spine slightly when upright. The WHO charts account for this difference, so you won’t see a false “dip” at age 2.
If your child is under 2 but won’t lie down, a healthcare provider can measure standing height and add 0.7 cm to convert it to length. If a child over 2 can’t stand, the reverse applies: measure lying down and subtract 0.7 cm.
Head Circumference Milestones for Girls
Head circumference grows rapidly in the first year and then slows considerably. For girls, the median (50th percentile) values at key ages are:
- Birth: 33.9 cm
- 3 months: 39.5 cm
- 6 months: 42.2 cm
- 12 months: 44.9 cm
- 2 years: 47.2 cm
- 3 years: 48.5 cm
- 5 years: 49.9 cm
At birth, the normal range spans from about 31.1 cm (1st percentile) to 36.6 cm (99th percentile). By age 5, that range narrows to 46.6 cm up to 53.2 cm. Notice how most of the growth happens in the first 12 months, when the median jumps by 11 cm. Over the next four years combined, it grows only another 5 cm. This rapid early growth reflects intense brain development in the first year of life.
What the Percentiles Actually Mean
A common misunderstanding is that a low percentile automatically means something is wrong. If your daughter is at the 15th percentile for weight, that simply means 15% of healthy girls her age weigh less and 85% weigh more. On its own, that’s a perfectly normal place to be. What matters more than any single number is the pattern over time.
The WHO uses cutoff values of roughly the 2nd and 98th percentiles (corresponding to 2 standard deviations from the median) to flag potentially abnormal growth. For girls under 2, the key thresholds are:
- Short stature: length-for-age below the 2nd percentile
- Low weight-for-length: below the 2nd percentile
- High weight-for-length: above the 98th percentile
For children aged 2 and older, BMI-for-age becomes the preferred way to assess body composition. A BMI at or above the 85th percentile is classified as overweight, and at or above the 95th percentile as obese.
Why Tracking the Trend Matters Most
A single measurement plotted on a growth chart is a snapshot. The real value comes from plotting multiple measurements over time and watching the curve. A girl who consistently tracks along the 25th percentile for both weight and length is growing normally. A girl who drops from the 50th percentile to the 10th over a few months is showing a pattern that needs investigation, even though the 10th percentile itself is within normal range.
This is why pediatricians plot growth at every well-child visit. Crossing two or more major percentile lines, either up or down, is the typical trigger for further evaluation. Upward crossing on weight-for-length may suggest overfeeding or an endocrine issue. Downward crossing on length-for-age could point to nutritional deficiency, a chronic illness, or sometimes just a genetic pattern where a child is settling into her own trajectory after birth.
Growth velocity, or how fast your daughter gains weight and length per month, provides another layer of information. The WHO publishes weight velocity standards for girls covering one-month increments from birth to 12 months. These are especially useful in the first year when growth is fastest and changes can happen quickly. A girl who is gaining weight steadily, even if she’s small, is in a very different situation from one whose weight gain has stalled.
How to Read the Chart Yourself
If you want to plot your daughter’s growth at home, you’ll need her exact age in months, her weight in kilograms, and her length or height in centimeters. Find her age along the bottom axis, her measurement along the side axis, and mark where they intersect. The curved line closest to that point tells you her approximate percentile.
The WHO provides free downloadable charts on its website in both percentile and z-score formats. Z-scores and percentiles convey the same information in different ways. Percentiles are easier to understand intuitively (your daughter is bigger than X% of girls her age), while z-scores are more useful for tracking children at the extremes of the growth range, where small percentile differences can represent significant clinical changes.
Keep in mind that premature babies need age-adjusted plotting. If your daughter was born four weeks early, her growth at 6 months of actual age should be plotted at 5 months on the chart. Most pediatricians use corrected age for preterm infants until around age 2.