Update on the implementation of the WHO child growth standards. 
In 2006, the World Health Organization (WHO) launched new growth standards for application to all children regardless of ethnicity, socioeconomic status and feeding mode.  By April 2011, 125 countries had adopted the WHO standards, another 25 were considering their adoption, and 30 had not adopted them.  Reasons for adoption included: (1) providing a more reliable tool for assessing growth that is consistent with the Global Strategy for Infant and Young Child Feeding; (2) protecting and promoting breastfeeding; (3) enabling monitoring of malnutrition's double burden, stunting and overweight; (4) promoting healthy growth and protecting the right of children to reach their full genetic potential, and (5) harmonizing national growth assessment systems.  In adopting the new standards many countries switched from weight-for-age only to multiple indicators.  Weight-for-age was adopted almost universally, followed by length/height-for-age (104 countries) and weight-for-length/height (88 countries).  Several countries (36) reported newly introducing body mass index-for-age.  Most countries opted for sex-specific charts and the z-score classification.  Many redesigned their child health records and updated recommendations on infant feeding, immunization and other health messages.  The scrutiny that the WHO standards have undergone is without precedent in the history of developing and applying growth assessment tools.  Governments set up committees to scrutinize the new standards before deciding to adopt them and professional groups conducted thorough examination of the standards.  The detailed evaluation allowed to assess the impact of the new standards and document their robustness and benefits for child health programmes.  In sum, 5 years after their release, the WHO growth standards have been widely implemented.  Countries have adopted and harmonized best practices in child growth assessment, and established the breastfed infant as the norm against which to assess compliance with children's right to achieve their full genetic growth potential.