Q: My baby is small but my pediatric provider says she is "following the curve" so he is not worried. What does that mean? I'm still worried!
A. If your baby is "following the curve" of the growth chart, she's paralleling one of the percentile lines on the chart, and the odds are good that her caloric intake is fine, no matter how much or how little milk she seems to be drinking.
On the other hand, if she is "falling off the curve," she's dipping below two or more percentile lines on the growth chart, and she may have inadequate nutritional intake. This could represent a real problem.
Growth Charts: How They Work
There are separate growth charts for weight, height, and head circumference.
These simply represent the average weight, height, or head circumference of a bunch of normal children. You will see the percentile lines on the chart running parallel to each other. The percentile lines include 5%, 10%, 25%, 50%, 75%, 90%, and 95%. (For more information, see the CDC's web site: www.cdc.gov/growthcharts/).
If a child's weight is at the 50th percentile line, that means that out of 100 normal children her age, 50 will be bigger than she is and 50 smaller. Similarly, if she is in the 75th percentile, that means that she is bigger than 75 children and smaller than only 25, compared with 100 children her age.
What Growth Charts Tell Us
The growth percentiles by themselves don't say much. What really matters is the rate of growth:
- A normal rate of growth means the child's growth points closely follow a percentile line on the chart.
- We usually don't worry about insufficient (or excessive) growth until a child's growth rate has crossed at least two percentile lines (e.g., from above the 90th percentile to below the 50th).
- If a child's weight, height, or head size is below the 5th percentile, it's important to see if her growth points have always paralleled the 5th percentile line -- which would mean her growth rate is normal -- or if she is suddenly falling further behind, which is more concerning.
To see if your child is too skinny or overweight, there is a "weight for height" chart or a "BMI" index. These tell if your child's weight is close to what it should be, given her height.
How to Tell If Growth Could Be a Problem
One of the first signs that a child is not getting enough calories is when her weight increases at a much slower rate than her height and begins to fall below two percentile lines.
- Depending on the extent of the poor caloric intake, the child's height could become "stunted," that is, the height begins descending on the growth chart.
- If the lack of nutrition is severe and continues for an extended period of time, the head growth slows down, indicating that there are not enough calories for the brain to grow at a normal rate.
Similarly, a steady increase in weight, while the child's height increases at a much slower rate, indicates she may be putting too much extra meat on her bones. This can be a good thing or an early sign of a risk of obesity.
Put the growth chart into context. No child's growth and development is always so smooth and perfect like the lines of the chart. Kids bounce up and down the growth charts, depending on appetite, feeding issues, illnesses, brief feeding strikes, etc.
Consider other signs of good health. Does your child appear otherwise happy and healthy? Is she making nice developmental progress? If the answers are yes, a problem is less likely.
When to Worry
If your child's growth rate slows down (weight, height, or head size) and she falls below two percentile lines, then you should explore the reason for the poor growth.
Dr. P's Pearl
Don't obsess about every up and down of your infant's growth chart. It's only potentially a problem when there is a persistent downward trend, usually lasting many months.