Stunted growth is a reduced growth rate in human development. It is a primary manifestation of malnutrition in early childhood, including malnutrition during fetal development brought on by the malnourished mother. According to the latest UN estimates, an estimated 162 million children under 5 years of age, or 25%, were stunted in 2012. More than 90% of the world's stunted children live in Africa and Asia, where respectively 36% and 56% of children are affected. Once established, stunting and its effects typically become permanent. Stunted children may never regain the height lost as a result of stunting, and most children will never gain the corresponding body weight. It also leads to premature death later in life because vital organs never fully develop during childhood.
Growth stunting is identified by comparing measurements of children's heights to the World Health Organization 2006 growth reference population: children who fall below the fifth percentile of the reference population in height for age are defined as stunted, regardless of the reason. As an indicator of nutritional status, comparisons of children's measurements with growth reference curves may be used differently for populations of children than for individual children. The fact that an individual child falls below the fifth percentile for height for age on a growth reference curve may reflect normal variation in growth within a population: the individual child may be short simply because both parents carried genes for shortness and not because of inadequate nutrition. However, if substantially more than 5% of an identified child population have height for age that is less than the fifth percentile on the reference curve, then the population is said to have a higher-than-expected prevalence of stunting, and malnutrition is generally the first cause considered.
One study conducted in a rural area in Zimbabwe illustrates the impact malnutrition has on growth. The area is known for poor farming conditions and prevalent malnourishment. Children ages 6–17 in the area were assessed for height, weight, and body mass index (BMI). The data recorded was compared with both American and other African countries average heights. Compared with the American averages, the Zimbabwean boys' height and weight dropped as low as the 10th percentile in some age groups and showed no sign of catch-up growth during the mid-teens. Zimbabwean girls' height and weight were not as low, but did drop as low as the 25th percentile. However, catch-up growth did occur during mid-teens and by 16 and 17, the girls average was close to the 50th percentile. Olivier, Semproli, Pettener, and Toselli, sums it up by saying that "the adverse socioeconomic environment and the low levels of food availability compromise and probably delay the physical development of the affected children in all phases of growth." Also, these data support the theory that lower than average size at early ages could be due to an adaptive mechanism reacting to low food intake.
Stunted growth in animals
- United Nations Children's Fund, World Health Organization, The World Bank. UNICEFWHO- World Bank Joint Child Malnutrition Estimates. (http://data.unicef.org/resources/2013/webapps/nutrition)
- Olivieri, F., Semproli, S.,Pettener, D., & Toselli, S. (2007). Growth and malnutrition of rural zimbabwean children (6-17 years of age). American Journal of Physical Anthropology, 136(2), 214-222. doi:10.1002/ajpa.20797