Percentiles are used as a clinical measurement to ascertain the growth and size patterns for children in the United States. The Centers for Disease Control and Prevention has developed a Body Mass Index calculator, and the World Health Organization has published growth charts. Both provide a healthy range for children.
Body Mass Index, known as BMI, is a person's weight in kilograms divided by the square of height in meters, explains About.com. Being underweight or having a high BMI can lead to a variety of health-related issues. Healthy weight ranges include anything between the 5th and 85th percentile on the CDC growth chart. A large variance is given due to the impact of a child's age, sex, height and weight.
The WHO has established growth charts that are commonly recognized as the leading source for height charts, in particular for breastfed babies, notes About.com. A child's percentile on the growth charts doesn't necessarily indicate how well he is growing. It is far more important to review a child's growth over time. This is due to variations in growth, including unpredictable growth spurts, that can result in different percentiles at different times.
Regardless of where a child's height or weight falls on the charts, it is important to discuss any concerns about a child's growth with a health care provider.