Stunted growth
Stunted growth, also known as stunting or linear growth failure, is defined as impaired growth and development manifested by low height-for-age.[1] It is a primary manifestation of malnutrition (or more precisely chronic undernutrition) and recurrent infections, such as diarrhea and helminthiasis, in early childhood and even before birth, due to malnutrition during fetal development brought on by a malnourished mother. The definition of stunting according to the World Health Organization (WHO) is for the "height-for-age" value to be less than two standard deviations of the median of WHO Child Growth Standards.[2] Stunted growth is usually associated with poverty, unsanitary environmental conditions, maternal undernutrition, frequent illness, and/or inappropriate feeding practice and care during early years of life.
For stunting of growth in plants, see Stunt (botany). For causes other than malnutrition, see Short stature.Stunted growth
Stunting, nutritional stunting
As of 2020, an estimated 149 million children under 5 years of age, are stunted worldwide.[3] More than 85% of the world's stunted children live in Africa and Asia.[4] 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. Living in an environment where many people defecate in the open due to lack of sanitation, is an important cause of stunted growth in children, for example in India.[5]
Stunted growth in children has the following public health impacts apart from the obvious impact of shorter stature of the person affected:
The impact of stunting on child development has been established in multiple studies.[7] If a child is stunted at age 2 they will have higher risk of poor cognitive and educational achievement in life, with subsequent socio-economic and inter-generational consequences.[8][7] Multi-country studies have also suggested that stunting is associated with reductions in schooling, decreased economic productivity and poverty.[9] Stunted children also display higher risk of developing chronic non-communicable conditions such as diabetes and obesity as adults.[8][9] If a stunted child undergoes substantial weight gain after age 2, there is a higher chance of becoming obese. This is believed to be caused by metabolic changes produced by chronic malnutrition, that can produce metabolic imbalances if the individual is exposed to excessive or poor quality diets as an adult.[8][9] This can lead to higher risk of developing other related non-communicable diseases such as hypertension, coronary heart disease, metabolic syndrome and stroke.[8][9]
At societal level, stunted individuals do not fulfill their physical and cognitive developmental potential and will not be able to contribute maximally to society. Stunting can therefore limit economic development and productivity, and it has been estimated that it can affect a country's GDP up to 3%.[8][7][9]
Stunting is highly prevalent in low- and middle income countries (LMICs) and has severe consequences including increased risk of infections,[10] mortality[11][12] and loss of human capital.[10][13] The global prevalence of stunting decreased from 33% to 23% between 2000 and 2016.[14] Meanwhile, 37% of children in South Asia are stunted, and due to a large population size, the region bears about 40% of the global burden of stunting.[15]
Diagnosis[edit]
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. The lower than fifth percentile corresponds to less than two standard deviations of the WHO Child Growth Standards median.
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.