What To Know About Your Baby’s Height and Weight Percentile

As parents and caregivers, we watch our babies grow with awe. But it can be hard not to fall into the comparison trap—especially when it comes to their growth. With what may feel like a heavy emphasis on your child's height and weight at each well-baby checkup, you may find yourself comparing your child's size with other babies their age. You may even wonder whether their height or weight percentile is a sign that they're developmentally ahead or behind. (The short answer is no!)

Comparisons to other babies won't tell you much about your own baby's progress, says Ben Danielson, MD, a pediatrician and clinical professor of pediatrics at the University of Washington in Seattle. Like grown-ups, babies come in all shapes and sizes—and meet growth and developmental milestones according to their own timetables. Growth charts are simply one tool healthcare providers use to track growth over time and a child's relative weight and height at certain ages.

Here, pediatricians share the nitty-gritty on baby weight and height percentiles and put your worries to rest by answering the most common questions about baby growth charts and weight and height percentiles.

What Does My Baby’s Weight and Height Percentile Mean?

At each checkup, your baby's weight, length, and head circumference are plotted on a growth chart for their sex and age. If your child's height is at the 75th percentile, for instance, it means that they are as tall as or taller than 75% of the kids of the same sex and age group.

Any number between the 5th percentile and the 95th is considered "normal." Whether the measurements are high or low, they should follow a consistent curve on the growth chart over the first year.

"Your baby's position on the chart means very little to us," says Robert Eden, MD, a pediatrician and clinical assistant professor of pediatrics at Brown University Medical School in Providence, Rhode Island. "What matters is whether [they're] growing in a predictable trend." There are bound to be small variations from checkup to checkup, but any dramatic change is a red flag, and your doctor will want to keep closer tabs on your child.

What If My Baby Is Below the 50th Percentile for Weight or Height?

If your baby is below the 50th percentile in weight, you may be tempted to try to feed them more. Don't, advises Dr. Eden. There is no need to overfeed your baby. Their height and weight are perfectly healthy at the lower percentile as long as their growth increases steadily. It's only worrisome if your baby is at the very bottom of the chart and/or is not growing over time. Your baby's doctor will be tracking their growth and look for possible causes and treatments if needed.

What If My Baby Is Above the 50th Percentile for Weight or Height?

Your baby's weight does not typically predict future health issues unless it is radically out of proportion to their height. Research shows that over half of infants classified as being overweight were not overweight by age 8. The reverse is also true—most 8-year-olds who are overweight had average weights as babies. But no matter what your baby weighs, never restrict their food intake; they need calories and fat so their body and brain can grow.

"Having a large baby is often just a sign that everything went well during your pregnancy," says Daniel Rauch, MD, a board-certified pediatrician at Hackensack Meridian Health, New Jersey. (Your baby may have also been larger than average if you had gestational diabetes.) But once out of the uterus, genetics take over, and babies will show their true growth patterns between 9 and 18 months, explains Dr. Rauch.

Should My Baby’s Height and Weight Be in the Same Percentile?

Conventional wisdom holds that a baby's height, weight, and head circumference should be in the same percentile. While that's often the case, don't fret if your baby's percentiles seem out of whack. That's common. During a growth spurt, a baby's length may shoot up or they may gain weight quickly, causing their growth-chart percentiles to diverge.

Should I Be Concerned if My Baby Has a Big Head?

Of all your child's organs, their brain grows most rapidly, with the skull expanding right along with it. That's why your pediatrician so conscientiously measures head circumference—to ensure that your baby's brain is developing properly. One way to tell that a baby is significantly undernourished is that they stop gaining height and weight, while their head continues to grow at a normal rate (the body automatically reserves calories for all-important brain growth).

If a baby's head seems particularly large in relation to their height and weight, the doctor may measure the parents' heads, since this characteristic runs in families. They may also run other tests to make sure nothing else is causing a large head or macrocephaly. However, having a larger-than-average head is typically just a normal variation and not cause for concern.

Will My Preemie Catch Up to an Average Percentile for Weight and Height?

Although babies born preterm (before the 37th week of pregnancy) are smaller than full-term babies at birth, most will catch up with time. By 2, most premature babies have caught up with their full-term counterparts.

But there are exceptions. Being a multiple or being extremely premature, for example, can affect a baby's future size, says John Walburn, MD, a pediatrician and former professor of pediatrics at the University of Nebraska Medical Center. "Some of the smallest preemies never quite catch up, no matter how well nourished they are." However, that's nothing to worry about as long as they are consistently growing.

What if My Child Isn’t Growing as Expected?

"Failure to thrive" is a scary phrase that pediatricians use when a baby, toddler, or preschooler does not gain weight or height at an expected rate. It can also be the case when a child loses a significant amount of weight.

"We're not worried about the short-term effects of a stomach bug, but if your child drops significantly on the weight charts, your doctor should notice," says Lynnette J. Mazur, MD, MPH, FAAP, a pediatrician and professor of pediatrics at the UTHealth Houston.

Your medical provider will discuss strategies to improve your baby's diet. Failure to thrive can also indicate an infection, hormonal issues, an allergy, or a chronic disease such as diabetes, so if your child is dropping weight, consult your medical provider.

If My Child Doesn’t Sleep Well, Will It Stunt Growth?

Kids need rest to thrive, and their bodies release growth hormones during sleep. But even if your child refuses to nap or wakes often at night, they likely are getting enough sleep to grow. If your child is a snorer or a mouth breather or pauses in their breathing when asleep, tell your doctor. These are signs of sleep-disordered breathing, which is treatable.

How Much Does Diet Impact Growth?

"Genes are the most important factor, but you can't reach your genetic potential if you're not adequately nourished," explains Dr. Rauch.

If your child is eating a balanced diet, they probably don't need a multivitamin. However, the American Academy of Pediatrics (AAP) recommends that all infants, children, and adolescents get a daily dose of 400 IU of vitamin D, which is essential for healthy growth.

Since it's hard to get enough vitamin D from food alone, your child will probably need to take a daily supplement soon after they are born, unless they get at least 34 ounces of vitamin D-fortified formula per day.

Should I Be Worried if My Baby Suddenly Gains or Loses Weight or Height Percentile on a Growth Chart?

Probably not. Though growth charts help in spotting such fluctuations, the reality is that a baby's growth is often marked by variation—some will have a nice even curve, and some will have peaks and valleys. Because they grow in leaps, it's normal for babies to slide up and down the charts a bit as part of typical growth patterns. The key is how fast and drastic the transition is.

If your baby has been at the 50th percentile in weight or height and drops to the 5th, for instance, the doctor will want to explore why the growth pattern has been interrupted. Possible causes include feeding issues or illnesses, such as diabetes or other endocrine problems. Other conditions could lead to a dramatic jump in growth. More often, though, the cause is a growth spurt or improved nutrition.