Creating the WHO Child Growth Standards

Background

In 1993, the WHO created a working group on infant growth.^[1] The working group reviewed the limitations of the existing international reference ^[2], and recommended a new approach.

The working group concluded that child growth standards, rather than a reference, were necessary. The standards would:

• Describe how infants and young children should grow in all settings rather than how they do grow in a specific setting and time.
  
• Reflect normal growth under optimal environmental, behavioral, and health conditions, such as predominantly breastfeeding for at least 4 months.

The study used to create these standards was called the WHO Multicentre Growth Reference Study^[3].

WHO Multicentre Growth Reference Study (MGRS)

The WHO MGRS aimed to generate new growth charts for assessing the growth of infants and young children worldwide. The MGRS, conducted from 1997 to 2003, included a global sample of infants and children. The six sites were Pelotas, Brazil; Accra, Ghana; Delhi, India; Oslo, Norway; Muscat, Oman; and Davis, California, United States.

• Communities in the study^[4] were selected based on:
  • High socioeconomic status.
  • Low altitude (less than 1,500 m/less than 4,921 feet).
  • Low population mobility, allowing for a two-year follow-up.
  • A minimum of 20% of mothers in the community followed international feeding recommendations.
• Study sites had to have a research institution capable of conducting the study.
• Feeding criteria specified infants had to follow international infant feeding recommendations:
  • Predominantly breastfeeding for at least four months.
  • Introducing complementary foods by at least six months but not before four months.
  • Continued breastfeeding for at least 12 months (no upper limit on breastfeeding duration).
• Study sites had to have a breastfeeding support system that included:
  • Lactation consultants to help mothers address any problems with breastfeeding quickly.
  • Appropriate counseling to help mothers with complementary feeding.
• Exclusion criteria included:
  • Maternal smoking during pregnancy or lactation.
  • Prematurity (less than 37 weeks gestation).
  • High gestational age (greater than or equal to 42 weeks).
  • Multiple births.
  • Substantial morbidity.
  • Low socioeconomic status.
  • Mother's unwillingness to follow feeding criteria.

A primary study hypothesis was that infants and young children have the potential to grow similarly. This potential growth is not influenced by their race or ethnicity or place of birth, as long as they are breastfed, living in a healthy environment, and have adequate nutrition. The study confirmed the hypothesis. The mean length measurements from birth to 24 months in the six sites were virtually identical.

After completing the Multicentre Growth Reference Study, WHO collaborated with several organizations to develop the WHO Child Growth Standards to replace the 1977 NCHS/WHO growth references. The 1977 references were previously being used internationally. The collaborating organizations included the United Nations University Food and Nutrition Program, United Nations Children’s Fund, CDC, several governments, and others.

Test your knowledge

1. The WHO Child Growth Standards were developed to describe optimal growth among infants and children.
   1. True
   2. False
2. The United States was not included as a study country where data were collected to create the WHO growth standard charts.
   1. True
   2. False

See answers

Question 1A

Question 2B