You are likely familiar with growth charts and have been told of your infant’s/child’s growth percentiles. These are critical pieces of information in following a child’s health. These parameters are checked and plotted at each well-child visit at every age.
Young girl being measured by her doctor at her annual checkup.
I frequently saw children referred for growth problems, whether height, weight, or small or large for age. These are common issues for pediatric endocrinologists to evaluate.
This article lets you know growth expectations in preterm and term infants, and children so that you feel comfortable when your doctor presents you with information.
What determines growth?
Growth depends on numerous factors that include:
Family history
Genetic factors
Birth factors - term or preterm, small or large for gestational age, low oxygen at birth
Chronic conditions
Pituitary function
Timing of puberty
Growth depends on more than just hormones.
I will present general guidelines pediatricians follow and typical growth expectations.
Baby being weighed on an infant scale. Infants should achieve an expected amount of weight gain over time by specific ages.
Let’s start with infancy. A term newborn should:
Double its birth weight by 4-5 months
Triple its birth weight around a year
Quadruple their birth weight by 2 - 2 ½ years
After the first couple of weeks of life, a term newborn should
Gain about ½ pound (8 ounces) each week or
Gain a pound every 2-3 weeks for the first 6 months
From 6-12 months, weight increase slows to ¼ to ⅓ pounds per week.
An infant grows 8-10 inches (20-25 cm) during the first year.
The length of a baby should
increase by 50% in the first year and
double by age 4.
By age two, they are about half of their adult height.
The size of your newborn and infant does not have much bearing on or predict their size as a child or adult.
Babies born prematurely or small for gestational age (SGA) may have different growing patterns. Preterm infants have growth charts separate from term infants. These smaller babies often track below and parallel to the regular growth chart for up to two years. There is no concern as long as they grow and gain weight consistently and are not falling further behind.
Fluctuations in growth can occur during the first few years, but other than illness, neither weight loss nor a slowing in linear growth (length) should happen. By age three, a toddler will settle on height and weight percentiles they should follow through childhood until puberty.
Toddler attempting to measure himself with a tape measure.
From age three until pubertal onset, a child should:
Grow 2-3 inches or 5-7 cm annually and
Gain 4-10 pounds yearly.
In doing so, they should track along the same percentiles until entering puberty.
Once in puberty, a child’s growth rate may double or triple, causing an acceleration in growth percentiles. Weight gain also occurs due to increased muscle mass and body fat.
What is a growth chart?
Examples of the CDC infant growth charts for boys (left) and girls (right) from term birth to 36 months for length (upper graph) and weight (lower graph). Age in months is across the top of the chart and measurements for length and weight along the vertical axis. The bottom and top line of each graph represents the 5th and 95th percentiles.
A growth chart is a graph of specific growth parameters - height, weight, and head size - for different ages and genders. Growth charts show a range of sizes for any given age compared to other children of the same age. The majority of children will fall somewhere between the 5th and 95th percentiles.
What do the percentiles mean?
The percentiles compare an individual's measurements to children the same age in the United States. For example, if a child’s weight plots at the 40%, then 40% of children the same age weigh less, and 60% weigh more than that child.
What if my child is in different percentiles for height and weight?
That is perfectly fine and reflects their body habitus. A child may be at a higher or lower percentile in their weight relative to their height. As long as each parameter tracks consistently, they don’t have to be in perfect proportion. In fact, most kids are not.
Most crucial is not where they plot at one point in time, but how they track over longer intervals. Deviations from this (growing or gaining weight too fast or too slowly, stopping in their growth, or losing weight) are all concerns that warrant further evaluation. The growth chart is a vital tool since it shows patterns over time.
When to be concerned?
The following occurrences prompt concern and are reasons for further investigation:
An infant’s head percentile that is growing too quickly (crossing upward in percentiles) or too slowly (crossing downward in percentiles)
Weight loss in an infant or young child
Acceleration in height before puberty with increasing height percentiles
Weight or height that plateaus over time without an increase
A rapid rise in weight while the height continues to track consistently
The best way to know if your baby and child are growing as expected is to keep regular checkups with your doctor so that they can be measured and plotted to look for changes. Should you have concerns, be sure to let them know.
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