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.

