Why do doctors monitor babies' growth over time?

Your baby's doctor looks for an overall growth pattern by measuring your baby's weight, length (or height), and head circumference and comparing it with both national averages and previous measurements. Sudden deviations from this pattern or extreme measurements may indicate a problem with taking in or absorbing nutrients, an illness, or a developmental problem. Use our growth percentile calculator to see how your baby compares to his or her peers.

What do "percentiles" mean?

Your baby's doctor will tell you that your baby ranks at a specific percentile on a growth chart. It's a way of comparing your baby with the full spectrum of babies nationally. If your baby is in the 25th percentile for weight, for example, this means that 25 percent of babies the same age and sex in the United States weigh less and 75 percent weigh more. Growth percentiles between the fifth and 95th are considered normal.

What if my baby seems ahead or behind?

Don't worry too much if your baby isn't close to average size (i.e., the 50th percentile). Your baby grows at an individual pace. Growth spurts may have your baby speeding up the chart one month or one year and then leveling back the next. Some babies are naturally larger or smaller because of their genetic background. Another reason not to fixate on a number on a growth chart is that your baby's well-being involves a variety of factors, including development, temperament, and activity level, not just growth. If you have concerns, talk to your baby's doctor and he or she will be able to tell you whether there's anything to be concerned about.

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