How Children Grow

Mother measuring daughter’s height and marking on wall at home

When you bring your child into Alzein Pediatrics, whether for a routine wellness visit or an urgent illness, we’ll most likely weigh and measure your child. Usually, your physician or NP  will give you some information about how your child has grown since you last visited our office. They may even plot your child’s development on a graph, or tell you where your child’s weight and height falls relative to other children, giving you a percentile. If your child is in the 50% percentile, that means about half of the children their age are taller (or weigh more) and half of the children are shorter (or weigh less).

That data doesn’t necessarily tell us how tall your child will be when they are an adult, or how much they will weigh. Infants grow very quickly in the first year, and then human growth slows, becoming more variable, so all the plot points and information can just become noise, especially if we don’t know how to use the information.

Let’s start at the start.

Most parents fret about the relative size of their child almost immediately, because infants normally lose between 5-10% of their birth weight in the first week of life. New parents might wait as long as two weeks to see their baby start to gain weight. Somewhere between 4 and 6 months, your baby’s weight should have doubled from birth. At one year, your baby should be about triple their birth weight. For example, a baby who was 7 pounds at birth should weigh about 14 pounds around 6 months of age, and about 21 pounds at their first birthday. Growth rate then begins slowing, to a rate of around 5 pounds a year until age 5. Growth typically continues at a slower, steady pace until the onset of puberty, anywhere between 9 and 15 years of age, when there’s one final growth spurt. All that sounds great in theory, but when you look around the local playground, not every 5-year-old who was a 7 lb. newborn weighs 41 pounds.

A little history.

With all that variability, what value do these growth charts have for parents and your pediatric healthcare providers? Growth charts in the U.S. were standardized by the CDC in the 1970s and then updated in the early 2000s with an eye toward accomplishing two goals: catching truly atypical health events and offering doctors a consistent overview of patient development over time.

NOTE: The CDC explicitly states that the charts are not intended to for diagnosis but only to provide “an overall clinical impression” of a child.

What does it all mean?

At best, these charts give your pediatrician an anticipated range of expectations for your child based on that typical pattern of growth, relative to what’s typical for the entire population of kids.

What about my child?

Your child’s Alzein Pediatrics physician or NP is much more likely to look at your individual child and their unique genetics to determine their overall health and expectations. For height especially, we look to the Two Years Times Two and the Mid-Parental Methods. Generally, we can predict how tall a child will be as adult by multiplying their height at age two by two. For instance, a toddler who is 35” tall on his second birthday will usually top out around 5’8” as an adult. The Mid-Parental Method looks more at the height of the parents. We combine the heights, divide by two and, for a boy, add 2.5”. For a girl, we subtract 2.5” For instance, if the father is 6” tall and the mother is 5’5”, a male child is likely to be 5’11”. A female child is more likely to wind up about 5’6”.

We may look deeper if your child’s percentiles don’t “match.” A high percentile in weight with a low percentile in height can indicate issues with overweight or obesity. A high percentile in height and low in weight might be thriving, eating or digestive issues – or it could be “tall and skinny” genes! If your child is suddenly falling in both percentiles, or suddenly increasing at a fast rate, we may also monitor that as well.

Have questions?

When you have concerns or questions about your child’s growth, just ask us! We’ll answer thoroughly at your child’s visit or through your child’s patient portal.

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