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

As parents, we watch our babies grow with awe. Yet, sometimes we may compare our child with others their age when we worry they aren't hitting a certain milestone. For example, we may wonder: Is the fact that my daughter isn't crawling a sign that she's developmentally behind? (The answer is no!)

But comparisons won't tell you much about your own baby's progress, says Ben Danielson, M.D., pediatrician and former senior medical director of Odessa Brown Children's Clinic in Seattle. Like grown-ups, babies come in a multitude of shapes and sizes. And they hit growth and developmental milestones according to their own timetables.

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

10 Common Baby Growth Chart Questions

What does my baby’s percentile mean?

At each checkup, your baby's weight, length, and head circumference are plotted on a growth chart. 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 in their 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, M.D., a clinical assistant professor of pediatrics at Brown University Medical School. "What matters is whether [they're] growing in a predictable trend." There are bound to be 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?

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. Even babies in a lower percentile will be fine as long as their growth remains steady.

What if my baby is above the 50th percentile?

Your baby's weight typically does not predict future issues unless it is radically out of proportion to their height. And 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, M.D., a board-certified pediatrician in Boston. (Your baby may have also been uncharacteristically big if you suffered from gestational diabetes.) But once out of the womb, genetics take over, and babies will show their true growth patterns between 9 and 18 months.

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 about a big head?

Of all your child's organs, their brain grows most rapidly, with the head 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.

Will my preemie catch up to an average percentile?

Although babies born preterm (before the 37th week of pregnancy) are small at birth, they will catch up most of the 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, M.D., says 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."

What if my child isn’t growing?

"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, M.D., M.P.H, F.A.A.P., professor of pediatrics at the UTHealth Houston.

Your medical provider will discuss strategies to improve their 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; their body releases 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 eating a balanced diet, your child probably doesn'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 D-fortified formula per day.

Should I be worried if my baby suddenly gains or loses weight or height 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 and drops to the 5th, for instance, the doctor will want to explore why the growth pattern has been interrupted. Possible causes include illnesses such as diabetes or other endocrine problems. There are also conditions that could lead to a dramatic jump in growth. More often, though, the cause is a growth spurt or improved nutrition.