Understanding Growth ChartsJennifer Beam
You may have noticed during typical well-child visits to your doctor or pediatrician, a practitioner whips out a chart with dots and lines that represent your child's growth in height, length and head circumference. Words like "percentile" and "body mass index" are used while parents nod their heads in understanding. But, if you're like many parents, it's only a partial understanding. Because each well-child visit combines brief discussions of growth charts with immunizations, a physical examination, and a briefing on the sleeping, eating, and development habits of your child, it may not seem crucial to ask for a dissertation on the meaning of growth charts during your allotted twenty minutes. However, after a closer look, these charts aren't difficult to understand and they can tell you and your doctor a great deal about the physical development of your child.
Growth charts were first developed by the National Center for Health Statistics in 1977. Their purpose is to serve as a tool to monitor growth and physical development in children. As more information has been collected, the charts have been revised over the years to include variables such as breast-fed and strictly formula-fed babies, premature babies, and Downs-Syndrome babies. In 2000, the CDC revised the charts and included a Body Mass Index. The Body Mass Index is calculated from weight and height measurements and has been a commonly used method to determine adult obesity. As the obesity rate in American children has risen, concerns about overweight children aided in the development of these new charts, but it isn't necessary to begin charting a child's BMI until they reach two years of age.
The charts are different for boys and girls and allow for the different growth rates of both sexes. Boys are typically longer or taller than girls are, but girls hit their pre-adolescent "growth-spurt" earlier than boys. In the case of pre and adolescent children, growth charts are primarily used to identify any potential weight problems by insuring a child's weight is proportionate with their height. With infants and toddlers, however, growth charts help establish a baseline for physical development and can detect many problems during those formidable first two years of growth.
Beginning at birth, a baby's weight and length is charted. At baby's first well-child visit, typically at two weeks, these measurements are taken again. It is normal for both the height and weight to vary slightly from the measurements taken at birth. Once a baby's length, weight, and head circumference are charted at two weeks, the individual child's baseline for further comparison is formed. During subsequent visits, the rate of growth should remain proportionate and this is merely one way a doctor monitors a child's growth.
Proportionate simply means that a child's weight, height, and head circumference remain in a relatively close percentile and that the percentile doesn't change drastically in one measurement without the others. For example, if at two weeks, all three measurements were charted in the fiftieth percentile, and then at two months, only the head circumference jumped into the sixty-fifth percentile, it may indicate to the doctor that a problem is present. In another for instance, if weight should drop drastically between visits, or even steadily between several visits, this would also indicate an area of concern to the doctor.
Percentile explains where a child's measurements fall in relation to other children. It's like comparing the weight, height, and head circumference of one child to 100 others. Let's say a twelve-month old baby's weight is at the 25th percentile. In this case, it means that the baby weighs the same or more than twenty-five percent of 100 other children by comparison, but less than the other seventy-five percent. Given information such as this alone, parents might be lead to believe that their baby is underweight, but providing their height and head circumference also falls around the 25th percentile, it means their growth is proportionate.
Due to the many variables that can apply, specialized growth charts are used when necessary. Health conditions can affect growth and therefore these conditions should be taken into consideration. Measurements under special conditions may be inconsistent if they are compared to the general population of children, but a good pediatrician will be able to adjust the charts and discern a comparison that is relative to the child. For example, a doctor can back the growth chart up for a premature baby. A baby born before his due date would be charted under the age group appropriate for his due date, not his birth date.
A number of other variables can come into play with or without extenuating health circumstances, but the growth charts simply provide a basis of comparison by which growth is monitored. Babies and young children are monitored for healthy growth and to detect any possible conditions that may be affecting their growth and development. Failure to thrive is one such condition that can be indicated and detected by data on the growth chart. Regardless of the data on any child's chart, if, under any circumstance, a parent is concerned about their child's growth or physical development, it should be addressed with the child's doctor.
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