Get access to over 1,300 articles and reader Q&As.
How sound is the data behind infant and childhood growth charts? We have a very active, happy, sweet, and small four-month old (like, third-percentile small). Our doctor, lactation consultants, and the internet all say we don’t need to be concerned about growth unless our child fails to follow the curve. But what does it mean to follow the curve when you’re at the very bottom? What happens if he falls off the curve entirely?
—Mom of a truly little “little one”
First, some background: Growth charts are simply a summary of the distribution of child sizes by age. The CDC develops these charts based largely on data from the National Health and Nutrition Examination Survey (NHANES), which is a nationally representative random sample. There are also World Health Organization growth charts, based on international data.
To slightly oversimplify, imagine just taking a random sample of kids, weighing and measuring them, and then generating a distribution for each age. That’s what the growth chart is.
When we say your child is at the 3rd percentile, that just means that if we took 100 randomly sampled children at that age, 97 of them would be larger than your kid. There is nothing inherently problematic about this! Some kids are bigger, some are smaller — just like adults. The predictive power for adult size is there, but it is actually fairly weak. So your child may well not be a smaller-than-average adult.
The place where doctors worry is when your child has “fallen off” their own curve, meaning that their growth has slowed relative to where they were. This is a concern regardless of where they start. If a child is at the 50th percentile at one visit and moves to the 20th, that may prompt the same concern that would be there if your child moved from the 3rd to the 1st percentile. In either case, it’s an indication that there might be a nutrition issue.
To be clear: most of the time, this is just random variation and not something to be worried about, but it is a flag to keep an eye on things. As long as your child is growing, even if they are small, it’s not something to be worried about!
Community Guidelines
Log in
The one thing I’d add is that following your own curve isn’t really a thing until 12 months. Babies can bounce all over the curves and be really fat or really small and change between visits, and it’s typically fine. Once the kid reaches 1 year, it might be more concerning if the child falls off her own curve.
I had a similar experience but on the other end it the chart for weight. My daughter was a heavy baby, heavy toddler, and now at 7 her BMI is higher than the ideal. My pediatrician asked about diet and activity level and when she realized she is an active kid that eats relatively healthy, she agreed that it’s her body type and she’s perfect as she is. She’s been consistent since she was born pretty much.
To whoever asked this question,
I was in the same boat with my first child, she was very small. She is now almost 7 and is still very small (5th percentile). My doctor isn’t worried at all because according to my daughters growth chart she still on HER growth curve and growing. Which basically means she continuously grows and stays within 5th percentile of her age group. So don’t worry as long as he is growing at his pace, he is good :).