Why is my breastfed baby getting smaller on the growth charts?

CDC vs. WHO growth curves

When you come in for well visits, we weigh and measure your baby and then plot them on the 2000 Centers for Disease Control CDC) growth charts. Those growth charts are where we get the percentiles that we put in the "little red book " that you got in the nursery. We follow those percentiles over time to gauge how well your baby is growing and to see if we need to intervene if the baby isn't growing the way they used to. Breastfed kids almost always start dropping percentiles as they get older.  And that can be alarming if you don't know why that's happening.

The CDC growth curves are based on population samples of the US.  The information for the growth charts was collected from five separate surveys of the population of the US done between 1963 and 1994. That data and the resulting growth curves show how kids are growing in the US.  They are a growth reference.

Breastfed infants who drop percentiles are doing what they are supposed to do on the CDC curves. As time goes on during the first year of life, fewer and fewer children are being breastfed.  By 9 months very few children are still getting breastmilk, and when breastfed kids are compared to formula fed ones, they will be smaller, leaner. Breastfed children will be "dropping off" of the curve simply because they aren't being compared to a jury of their peers, so to speak.

The World health Organization created a new set of growth curves to represent how kids should be growing.  These curves are growth standards.

The data for these curves was based on data  from children from Brazil, Ghana, India, Norway, Oman and the USA. They were based on children receiving the best nutrition, without an environmental smoke exposure, and are meant to represent the best physiological growth in infancy and childhood.  breastfed infants do not "drop off" these curves.

To plot your children on these curves (it's in kilograms, not pounds) or for more information, check out the WHO website for girls charts and boys charts.

updated May 22, 2007