Image from WHO's Child Growth Standards site
While I'm satisfied with the pediatrician's office, I know they do not use the World Health Organization's growth charts. Instead, they use the CDC's individual growth charts. I didn't think there was that big of a difference. Boy was I wrong. Here's the summary from a study published in the Morbidity and Mortality Weekly Report that is put out by the CDC:
In April 2006, the World Health Organization (WHO) released new international growth charts for children aged 0--59 months. Similar to the 2000 CDC growth charts, these charts describe weight for age, length (or stature) for age, weight for length (or stature), and body mass index for age. Whereas the WHO charts are growth standards, describing the growth of healthy children in optimal conditions, the CDC charts are a growth reference, describing how certain children grew in a particular place and time. However, in practice, clinicians use growth charts as standards rather than references.
In 2006, CDC, the National Institutes of Health, and the American Academy of Pediatrics convened an expert panel to review scientific evidence and discuss the potential use of the new WHO growth charts in clinical settings in the United States. On the basis of input from this expert panel, CDC recommends that clinicians in the United States use the 2006 WHO international growth charts, rather than the CDC growth charts, for children aged < 24 months (available at https://www.cdc.gov/growthcharts). The CDC growth charts should continue to be used for the assessment of growth in persons aged 2--19 years.
The recommendation to use the 2006 WHO international growth charts for children aged < 24 months is based on several considerations, including the recognition that breastfeeding is the recommended standard for infant feeding. In the WHO charts, the healthy breastfed infant is intended to be the standard against which all other infants are compared; 100% of the reference population of infants were breastfed for 12 months and were predominantly breastfed for at least 4 months. When using the WHO growth charts to screen for possible abnormal or unhealthy growth, use of the 2.3rd and 97.7th percentiles (or ±2 standard deviations) are recommended, rather than the 5th and 95th percentiles. Clinicians should be aware that fewer U.S. children will be identified as underweight using the WHO charts, slower growth among breastfed infants during ages 3--18 months is normal, and gaining weight more rapidly than is indicated on the WHO charts might signal early signs of overweight.
Okay, so what does all this mean?
The CDC is recommending that WHO charts be used on children under 24 months rather than their own charts. The children used to develop the WHO charts were all breastfed for 12 months and were breastfed primarily for at least 4 months. The CDC charts used information from national surveys and didn't necessarily take into account what the infants were fed. A reference for exclusively breastfed (per AAP's definition of exclusive breastfeeding) infants does not exist.
Parents of exclusively breastfed infants need to be sure that their baby is compared to other babies who are fed the same way. That matters because "healthy breastfed infants tend to grow more rapidly than their formula-fed peers in the first 2-3 months of life and less rapidly from 3 to 12 months." (source).
According to the CDC chart and his last height and weight, E is in the 10th percentile for weight. When I mapped it to the WHO charts, he was squarely in the 50th percentile. I went back and plotted other weight/height combinations and he falls along the 50th percentile curve almost every time! He's average and I'm thrilled!
I know I shouldn't worry because he's hitting his milestones and is happy and healthy, but it's a lot harder than that. I carry a lot of guilt about those first few days. I'll always have it, though I'm sure it will fade over time.
I learned about the difference between the two charts in my birth classes, but didn't think it was that big of a deal. I didn't realize the huge difference until I took the time to do my own charting. It doesn't sound like much, but to a mom who has had a hard time dealing with weight, the difference in percentiles is staggering! I'm even a little angry that the doctors office doesn't abide by the CDC's recommendation.
Lesson learned: make sure my child is compared to the group of infants who are being fed in the same way he is. I'll be pretty adamant about finding a pediatrician that follows the CDC's recommendation to use the WHO charts for any subsequent children.
I decided to harness that anger for good instead of evil. I emailed my pediatrician's main office with my concerns on not using the WHO charts and suggested they contact me to discuss it further. Maybe I can save some other new parents some worry. Lets see what they come back with.
Does your pediatrician use the WHO chart or the CDC chart?
PS - No apologies for the title, you should know I love a good (terrible) pun.