By Rebecca Costello, IBCLC

We sometimes hear from parents concerned that their breastfed children’s growth “slowing down” around 4 months – the baby’s weight percentile dropping and the baby slipping down the growth curve. Sometimes these concerns are accurate – but sometimes they are not! Why??

The fact is, some medical offices still use growth charts developed in 1977, based on a small sample of babies in Ohio who were primarily formula fed. Similarly, even the 2000 Centers for Disease Control (CDC) growth charts are based on a sample of mixed breast/formula feeders. Formula fed babies grow more slowly than breastfed babies in their first few months of life, then begin to grow more quickly than breastfed babies. When we chart breastfed babies on the formula fed growth chart, it makes breastfed babies look nice and high on the chart for the first few months, and then start to look like they are faltering.

What does it look like when breastfed babies are tracked on charts that accurately reflect their growth? To do that, the newest World Health Organization (WHO) growth charts are a far better choice than any of he CDC charts. The WHO charts are based on a worldwide sample of infants who received optimal breastfeeding and complementary feeding.

This article from the Journal of Nutrition does an excellent job of discussing some of the differences between the CDC and WHO growth charts. They have several great illustrations as well to help you visualize how the growth charts differ:

This chart shows the difference between weight-for-age curves in boys ages 0-60 months. You can see how around 4-6 months, the CDC chart line crosses over the WHO line and generally stays above – sometimes quite high above – the WHO line up through age 5.

This chart is even better, which shows how an average infant from the WHO sample would track on each chart. A baby who tracks normally on the WHO chart (staying fairly even in growth after an initial drop) looks very different on the CDC chart: after an initial rise the baby appears to slowly fall down the growth curve from the age of 2 months on.

The CDC formally recommends that all clinicians switch to the new WHO growth charts for ALL infants and toddlers up to 2 years of age. (Note that this means not just breastfed babies – the CDC recognizes that those charts reflect optimal infant growth, and that the more rapid growth of formula fed babies is a potential cause for concern.) Ask your baby’s care providers which charts they are using, and encourage them to use WHO charts! If your baby is still falling on the growth charts even on WHO charts, give your friendly WBWC MILC lactation consultants a call! After some detective work, we often find a simple fix to help families get growth back on track.