What Growth Charts Mean (and Should You Worry?)
“How’d it go at the pediatrician?”
“Well, great, because Emma’s head is in the 95th percentile, so she must be really smart! But she’s only in the 5th percentile for weight and the 10th for height—I’m a little worried. I know that Marcus was in the 85th percentile at this age, but the doctor didn’t seem to be worried. I wonder why?”
This may be a common type of conversation after a wellness visit—parents don’t really understand percentiles on growth charts. Despite reviewing growth charts in the doctor’s office, a 2009 study by the American Academy of Pediatrics showed that many parents don’t know how this information relates to their child’s health. What do the numbers mean?
Percentiles aren’t scores comparing your child to other children. It’s how she’s compares to herself. Dr. Kristina Powell of Pediatric Associates of Williamsburg explains:
“It’s about the progression of growth, not that point they are at today, whether that’s 5 percent or 95 percent. Genetically, we are all different and won’t be the same size. What’s important is that it continues on the same trajectory. We look for a shift that indicates they’ve stopped growing or that there’s been a huge jump,” she says.
Parents often come in upset about their child in the 5th percentile. Is there a problem? No, Powell says, as long as they are progressing in an expected direction. What pediatricians look for is a move over two percentile curves (there are nine total on both charts), which could indicate a medical issue whether they gain a lot of weight, or they stop growing. That’s why yearly checkups are so important to look for patterns over time.
Doctors also look at other signs like family history. “Maybe the parents are petite, or there’s a family history of larger heads,” Powell says. There are also nutritional concerns to consider, such as a lack of proper nutrition, since that can affect growth. Powell says she’d look for an underlying medical condition with lab tests, and also talking about healthy food and exercise. If it’s not a medical condition, it’s often a nutritional problem.
Growth charts for infants and toddlers
Concern heightens among parents regarding their children’s percentile during the infant and toddler years. But Powell says big shifts are often normal from 9 months to 2 years. Babies change physically once they are walking and feeding themselves.
The World Health Organization chart is used for children ages 0 -2 and then the Centers for Disease Control charts from ages 2-21. According to Powell, the reason that WHO charts are used in the early years are that they are the standard to aim for, based on data from six different countries, with exclusively breastfed babies who receive optimal nutrition for one year.
“Breastfed babies are leaner, especially after two months up to a year. Some doctors are not aware of this and diagnose babies as underweight,” Powell says. “So underweight is over-diagnosed with the CDC growth charts.”
Growth charts are not just for young children; pediatricians look for growth issues over time, including eating disorders, delayed puberty, underlying medical conditions that might affect nutrient absorption or the first signs of obesity. Tracking growth is an early alert system for doctors. But if a growth problem is indicated, what happens next?
Consulting a pediatric endocrinologist
Patients are usually referred to a pediatric endocrinologist, like Dr. Marta Satin-Smith from Children’s Hospital of The King’s Daughters in Norfolk, Va. The first tests she runs looks for hormone deficiencies that affect growth. “We also would screen for liver and kidney disease and as indicated by history for other chronic conditions such as celiac, inflammatory bowel disease, anemia and cystic fibrosis,” she says.
The most common diagnoses she sees are familial short stature and delayed puberty. She says this can be difficult emotionally for children who want to be taller. “Short stature, especially when associated with delayed puberty, can often be a major source of stress for a child,” she says.
If you suspect a growth issue, don’t run off to the pediatric endocrinologist. “Pediatricians are well-educated when it comes to evaluating growth velocity and determining if there is an issue that needs to be addressed by an endocrinologist. If a parent is concerned about growth and there is a family history, more frequent visits to the pediatrician may be necessary,” says Satin-Smith.
Some parents have learned to take the numbers in stride, like Rachel Lenahan, about her 4-year-old son Reese, who was in the 99th percentile for height, weight and head circumference. “It didn’t bother us because my side of the family is very tall. My dad is 6’6”. We are all fit and not overweight, and the large head circumference runs in the Lenahan family,” she says. “I just figured someone has to be on the high and low end, and it doesn’t mean that anything’s wrong. That’s why there are highs, lows and averages. Everybody fits somewhere!”
The growth of children from infants to young adults is an amazing biological process, but it happens over a long period of time. The best advice for parents is to ensure children get enough sleep, eat well and get regular exercise—and check in with their pediatricians regularly to keep an eye out for any potential issues.