Growth charts are a great tool that can be used to ensure your baby is properly developing. Unfortunately, the problem with growth charts is that they are often misinterpreted or misunderstood. It is easy to get caught up with percentiles and miss the real meaning behind growth charts, which is to monitor the trend in your baby’s growth over time. If you do, you will be amazed at how quickly your baby grows over the first year of life.
What are growth charts?
Growth charts compare your baby’s head size, height, and weight to standard numbers from babies of the same age.  The standard numbers represent a national average for each particular age and gender based on the weights and measurements of thousands of babies. Growth charts are used by pediatricians to monitor the growth of your baby and ensure his or her healthy development. Certain trends in your baby’s growth may indicate to your pediatrician that your baby has a health problem.
What do the percentiles mean?
The percentiles on a growth chart describe how your baby’s head size, height, and weight compare to other babies in his or her age range. [1,2] If your baby is in the 25th percentile, this means that 25% of babies weigh the same or less than him or her and 75% weigh more. Parents are often concerned about what percentile their baby falls into. However, it is the trend in your baby’s growth that is most important for determining his or her development patterns. Falling into a low percentile does not automatically mean that your baby is sick, not developing properly, or not eating enough. Babies may experience different weight fluctuations just as adults do. For example, your baby may have diarrhea prior to his or her check-up and lose some weight, but he or she will likely regain it soon after. If your baby’s growth over time has been following one of the percentile curves on the growth chart, he or she is most likely eating enough.  Many parents also worry because they think that their baby’s growth will predict whether he or she will be short, tall, slender, or overweight as an adult, but this is not the case.  It is best to discuss your baby’s growth trends with your pediatrician so you can see how your baby is progressing throughout the first years of his or her life.
Why is head size important?
Your pediatrician will measure the distance around your baby’s head to monitor for proper brain development.  The size of your baby’s head is proportional to the size of his or her brain. If your baby’s head is too small, the pediatrician may suspect that there is a problem with the development of your baby’s brain. A head size that is too large can be a potential warning that your baby may have fluid in his or her brain.
Which growth charts are used?
Until your baby reaches the age of 2 years, the CDC recommends that pediatricians use the WHO growth charts to monitor your baby’s growth.  The WHO growth charts provide standards for how babies should grow under ideal conditions. These standards are determined from babies that were primarily breastfed for at least the first 4 months of life. The WHO growth charts provide a better description of growth in babies than CDC growth charts. The CDC growth charts provide references for how babies in the U.S. grow during certain ages, but these patterns are not always ideal. CDC growth charts are used after your baby reaches 2 years old until the age of 20.
What type of trends are concerning to your pediatrician?
Certain trends may cause your pediatrician to question whether your baby is properly developing.  One type of trend that may be concerning is if your baby stays above the 90th percentile or below the 10th percentile for his or her age. Another concern is if your baby shows extreme changes in growth. For example, if your baby was in the 75th percentile at 6 months, then dropped to the 25th percentile or lower at 9 months, there may be a problem with your baby’s development. Your pediatrician will also monitor your baby to ensure that if your baby is growing in height, he or she continues to gain an appropriate amount of weight.
Watching your baby grow during the first few years of life can be an exciting time. It is important to monitor your baby’s growth patterns and not place too much emphasis on which percentile your baby falls into for his or her age. Your pediatrician will help you monitor the size of your baby’s head and trends in your baby’s height and weight to ensure that he or she is healthy and developing properly. Drastic fluctuations from one percentile to another should be discussed with your pediatrician because it may indicate that your baby has a health problem.
- U.S. National Library of Medicine. Growth Chart. MedlinePlus. Updated October 3, 2017. Accessed October 14, 2017.
- American Academy of Pediatrics. How to Read a Growth Chart: Percentiles Explained. healthychildren.org. Updated September 1, 2015. Accessed October 14, 2017.
- Parker SJ. Baby Growth Charts: What Influences Your Baby’s Growth? WebMD.
- U.S. National Library of Medicine. Head circumference. MedlinePlus. Updated October 3, 2017. Accessed October 15, 2017.
- WHO Growth Standards Are Recommended for Use in the U.S. for Infants and Children 0 to 2 Years of Age. Centers for Disease Control and Prevention. Updated September 9, 2010. Accessed October 14, 2017.