Frequently asked questions about the
2000 CDC growth charts

How can I get copies of the growth charts?

The charts are available on the NHANES Growth Charts Web and can be downloaded and copied. Also included on the Internet is a PowerPoint file of the growth charts -- these charts can be modified with different logos and then copies of the charts can be made from this file.

In addition, The American Academy of Pediatrics (AAP) is selling copies of the growth charts and some pharmaceutical companies are distributing them.

What is a percentile?

Percentiles are the most commonly used clinical indicator to assess the size and growth patterns of individual children in the United States. Percentiles rank the position of an individual by indicating what percent of the reference population the individual would equal or exceed. For example, on the weight-for-age growth charts, a 5-year-old girl whose weight is at the 25th percentile, weighs the same or more than 25 percent of the reference population of 5-year-old girls, and weighs less than 75 percent of the 5-year-old girls in the reference population.

What is a z-score?

A z-score is the deviation of the value for an individual from the mean value of the reference population divided by the standard deviation for the reference population. Because z-scores have a direct relationship with percentiles, a conversion can occur in either direction using a standard normal distribution table. Therefore, for every z-score there is a corresponding percentile and vice versa.

My child is at the 5th percentile on a chart, what should I do?

If you are concerned about your child’s growth, talk with your child's health care provider.

Are these charts appropriate for exclusively breast-fed babies?

The 2000 CDC growth charts can be used to assess the growth of exclusively breast-fed infants, however when interpreting the growth pattern one must take into account that mode of infant feeding can influence infant growth. In general, exclusively breast-fed infants tend to gain weight more rapidly in the first 2 to 3 months. From 6 to 12 months breast-fed infants tend to weigh less than formula-fed infants.

The 2000 CDC Growth Chart reference population includes data for both formula-fed and breast-fed infants, proportional to the distribution of breast- and formula-fed infants in the population. During the past two decades, approximately one-half of all infants in the United States received some breast milk and approximately one-third were breast-fed for 3 months or more. A Working Group of the World Health Organization is collecting data at seven international study centers to develop a new set of international growth charts for infants and preschoolers through age 5 years. These charts will be based on the growth of exclusively or predominantly breast-fed children.

What charts should be used for special populations?

The revised growth charts for the United States include data on low birthweight infants but do not include data on very low birth- weight infants (VLBW; less than 1,500 grams). Alternate charts are available to assess the growth of VLBW infants. The most recent are those developed from data collected in the National Institute of Child Health and Human Development Neonatal Research Network Centers (Ehrenkranz, 1999). However, these charts only extend to about 120 days uncorrected postnatal age or until a body weight of 2,000 grams is reached. Perhaps the best specific reference available for VLBW infants is the Infant Health and Development Program (IHDP) reference (Guo, et al. 1997; Guo, et al. 1996; and Roche, et al. 1997), although it has limitations. The IHDP growth charts may be considered to assess the growth of VLBW infants from an age corrected for gestation of 40 weeks to 36 months. However, the IHDP charts are based on data collected in 1985, which was before current medical and nutritional care practices were being used. Alternatively, the new 2000 CDC Growth Charts can be used to assess VLBW infants. Generally, their patterns of growth will be similar, but their measurements may fall in the lower percentiles. (See the training module: Children with Special Health Care Needs for a full discussion of the IHDP charts.)

A variety of health conditions affect growth status and there are specialized charts that may be considered for use with children affected by these conditions. (See the training module: Children with Special Health Care Needs for a full discussion of these charts.) These specialized growth charts provide useful growth references, but may have some limitations. Generally, they are developed from relatively small homogeneous samples and data used to develop the charts may have been obtained from inconsistent measuring techniques. One option is to plot the growth patterns of these children on both the specialized charts and the CDC growth charts. This will allow comparisons of growth to the general population of children and to the references for children identified with a given condition. In most cases, Body Mass Index-for-age charts are not available for special conditions and have not been validated for use with children whose body composition might differ from that of typical children. The CDC charts would provide a useful reference to monitor weight in relation to stature.

Ehrenkranz RA, Younes N, Lemons JA, Fanaroff AA, Donovan EF, Wright LL, Katsikiotis V, Tyson JE, Oh W, Shankaran S, Bauer CR, Korones SB, Stoll BJ, Stevenson DK, Papile L. Longitudinal growth of hospitalized very low birth weight infants. Pediatrics 104:280-9. 1999.

Guo SS, Roche AF, Chumlea WC, Casey PH, Moore WM. Growth in weight, recumbent length, and head circumference for preterm low-birthweight infants during the first three years of life using gestation-adjusted ages. Early Hum Dev 47:305-25. 1997.

Guo SS, Wholihan K, Roche AF, Chumlea WC, Casey PH. Weight-for-length reference data for preterm, low birth weight infants. Arch Pediatr Adolesc Med 150:964-70. 1996.

Roche AF, Guo SS, Wholihan K, Casey PH. Reference data for head circumference-for-length in preterm low-birth-weight infants. Arch Pediatr Adolesc Med 151:50-7. 1997.

This page last reviewed March 26, 2007