Parents tend to watch their baby’s weight pretty closely in the first year of life. If you’re exclusively breastfeeding, it’s a way to check that your baby is getting enough milk, and doctors use height and weight measurements as a general tool for tracking steady and healthy growth and let’s face it, weigh-ins are sometimes just plain fun.
That’s why it can be worrisome for some moms to see baby “dropping” in the percentiles for weight. It’s not uncommon for a baby who started out in the middle or high end of the weight chart to creep down well below the middle by a three- or six-month doctor’s visit. It’s unsettling when it happens, and many moms wonder if they’re producing enough milk.
But one of the reasons this dip in percentiles happens is that many pediatricians use height and weight charts that are based on populations of babies who are fed formula. For example, the CDC produced a growth chart in 2000 that used a population representative of babies in the U.S. (that is, about one half received some breast milk and one-third were breastfed for three months or more). As the CDC itself says, babies who are exclusively breastfed naturally tend to weigh less than formula-fed infants, especially after the third to sixth month of life. So if your baby’s pediatrician was using this chart, you might find that she drops lower and lower as the months go on, as she’s being compared with a population that is having more and more formula in their diet.
Why would formula fed babies gain more weight? Some think it has to do with caloric content – breast milk changes over the first year in its nutrition (more or less fat, for example, as your baby grows), whereas formula always provides the same number of calories.
Babies also become easily distracted around the three-month mark, because their brains are growing quickly and the outside world (the one beyond mom’s loving gaze) is becoming increasingly fascinating. If you’re nursing, short, frequent feedings are the standard at this age, and sometimes a baby’s weight will naturally dip as a result.
The World Health Organization has a set of growth charts that are a more accurate and useful measure of your baby’s height and weight. In fact, just recently, the CDC recommended that all pediatricians use these WHO charts for babies ages 0 to 24 months. The charts are based on a very large international sample of infants who were exclusively breastfed until at least four months and at least partially breastfed for 12 months or more, with no solid foods until six months.
All babies look heavier on the WHO chart, and a breastfed baby is more likely to stay on target for weight when being compared with this sample. Even though pediatricians are recommended to use the WHO charts, it will take some time for the switch to happen in most doctor’s offices, so ask your pediatrician which charts she’s using if either of you are concerned.
Remember that a growth chart reading is not a test (it’s hard to do when everyone around you is rooting for the highest score!)
For more on tracking your baby’s growth, check out the CDC’s full recommendation on height and weight charts.
Got a baby boy? Here’s the WHO growth chart from birth to 24 months
Got a baby girl? Here’s the WHO growth chart from birth to 24 months