Children grow at different rates. A causal glance around a school classroom will easily verify the differences. Growth rate and size are determined by many factors including genetics, gender, nutrition, hormones, physical activity, parental size and more. Parents may wonder what normal growth should be for their child. To help answer the question, pediatricians have used standard growth charts since 1977 as one tool to chart a child’s development.
Growth charts simply indicate average growth patterns for length, height, body mass and weight of children. Head circumference is also charted for infants up to age one as a tool to help determine if the brain is developing at an average rate. Different charts are used for boys and girls as their growth rates differ. Charts designed by the World Health Organization are most often used from infancy to age two. Charts prepared by the U.S. Center for Disease Control are preferred for children between two and eighteen years of age.
Rather than labeling growth as normal, doctors will often discuss height and weight in terms of percentiles. Percentiles are based on growth measurements taken from thousands of children over time. For example, a child who charts in the 60th percentile in height simply means that the child is taller than 60 out of 100 healthy children his age and shorter than 40 out of 100.
Being in a high or low percentile does not indicate, by itself, that a health or growth problem exists. There is no ideal number. Falling substantially above or below the 50th percentile on a single checkup is not usually cause for concern. The chart’s value comes from plotting growth over time. A consistent growth pattern over time with height and weight gaining in proportion to one another is more important than placement at a specific percentile.
Parents should begin asking questions if the growth rate and percentile placement changes substantially. If a child is tracking at the 60th percentile for weight over several years but then drops to the 25th percentile, meaning 75% of children his age weigh more, that may raise concerns about diet and nutrition. Questions might also be raised if the percentiles for weight and height substantially differ. For example, if height and weight consistently track at the 30th percentile over time but weight suddenly changes from the 30th to the 70th percentile, this suggests the child is gaining weight faster than he is getting taller.
Head circumference is an important measurement for babies. A head that is unusually larger or smaller than average may indicate a health or development issue. Similarly, if the circumference stops increasing or increases more quickly than a chart suggests is average, parents may have cause for concern.
Growth is just one sign of general health and development. Growth charts and calculators can be found online for parents wanting to track development between doctor visits. Just remember growth charts cannot be viewed in isolation but must be interpreted with consideration of a child’s overall environment and well-being.