Every baby grows at a different pace. Given the wide range of “normal” sizes, it’s hard to know whether your child measures up to standards. That’s why pediatricians track physical developments like length, weight, and head circumference with baby growth charts.
Genetics play a major role in a baby’s physical development – as do factors like environment, nutrition, activity level, and health condition. Even breastfed babies have different weight and height standards than their formula-fed counterparts. Thanks to these discrepancies, many parents wonder what a “normal” baby should look like, and they worry if their little one is bigger or smaller than other infants.
To answer these questions, the National Center for Health Statistics (NCHS) developed the first chart of child growth standards in 1977. The Centers for Disease Control and Prevention (CDC) has since analyzed up-to-date weight and height statistics, and they released new charts in 2000. The World Health Organization (WHO) also distributed international baby growth rate charts in 2006. Per the CDC’s recommendation, doctors and parents should refer to the WHO chart for children 0 to 2 years of age in the United States, and the CDC chart for children over 2 years old. You’ll find links to all charts at the bottom of the page.
Most charts measure length, weight, and head circumference.
Length: Using a tape measure, a doctor determines the distance from your baby’s head to his feet – usually while he’s stretched on an exam table.
Weight: A baby scale provides the best weight measurements. If your baby is under 12 months, you’ll probably need to take of his clothing before laying him on the scale.
Head Circumference: Also taken with a tape measure, head circumference clues you into baby’s brain development. A too-big head may signal a condition called hydrocephalus, characterized by excess fluid on the brain. On the other hand, if the distance around the head seems small, the baby may have developmental delays.
Pediatricians take these measurements at Baby’s regular wellness exams. Plotting the information on a growth chart lets them notice patterns and consistencies. Growth charts also compare your baby’s measurements with those of the average infant. It’s important to note that separate growth charts exist for boys and girls. Kids with certain conditions, such as Down syndrome or prematurity, may also have a different growth curve chart.
Growth charts can be hard to decipher at first glance. Here’s how to read WHO and CDC baby growth charts for length/weight, which are linked at the bottom of the article:
Locate your child’s length or weight (depending on what you’re measuring) on the left- or right-hand side of the grid, also called the Y-axis.
Find your baby’s monthly age on the top of the graph, also called the X-axis.
Follow the lines until they intersect. They should cross somewhere along the curves, which represent percentiles.
Follow the curve to see the percentiles on the right-hand side of the graph. The percentile lines show your baby’s measurements compared with other baby’s measurements.
In general, higher percentiles means your kid has bigger measurements than average – and vice versa for smaller percentiles. For example, if the curved line is “75” when measuring length, then your baby is in the 75th percentile for length. This means that 25% of babies are taller than your child, and 75% of babies are shorter than your child.
Instead of analyzing the actual measurements, doctors pay attention to patterns and consistencies on the growth charts. A constantly-growing, proportionate baby doesn’t raise any red flags – but a noticeable change in measurements should be closely examined.
For instance, having a lower weight and length for age isn’t usually worrisome; it might mean Baby has a genetic predisposition to being short and skinny. But if he goes from a high weight percentile (like 80th) to a low weight percentile (like 25th), then he’s probably not eating enough. He might also have a health condition that causes weight loss, such as celiac disease. On the other hand, gaining lots of weight for age means Baby is eating too much, which could lead to future health and weight problems.
Remember that all babies grow at different paces. Measuring at the 50th percentile isn’t better or worse than the 15th, 70th, or 99th percentile. As long as your baby is experiencing normal growth patterns, he will likely grow up happy and healthy.