Stunting refers to the failure to reach one's full potential for length. The WHO has developed standards to describe normal child growth applicable to children of all ethnicities and socio-economic backgrounds. If a child falls far enough below the height that is normally expected of children of this age, the child is considered to be stunted.
According to the World Health Organisation (WHO), children are defined as stunted if their height-for-age is more than two standard deviations below the Child Growth Standards median. In other words, a child who is stunted is considered too short for their age.
Stunted growth often starts in utero and continues after birth. Studies have found that the 1000-day window from conception to a child's second birthday plays a pivotal role in the child's physical and mental development and gives a strong indication of whether the child will become stunted.
Poor maternal health and nutrition, poor infant and young child feeding practices, repeated infection and inadequate opportunities to play and learn are factors that can impede child growth and development.
A mother's nutritional and health status is closely linked to her child's early growth and development during and after the pregnancy. The developing embryo in the womb relies on the nutritional intake of its mother to fuel its growth.
Intrauterine growth restriction, for example, due to maternal undernutrition (estimated by rates of low birth weight) accounts for 20% of childhood stunting, and the likelihood of stunting increases if the mother is infected with malaria, intestinal worms or HIV during pregnancy.
Competition for nutrients between a still growing mother and her foetus can occur in the context of adolescent pregnancy. In addition, short birth spacing has been found to impact a mother's nutrient reserves negatively.
The baby's dependency on its mother's nutritional status continues after birth through breastfeeding for the first six months of a baby’s life.
Starting at six months, an infant's need for nutrients exceeds what can be provided by breast milk alone. Therefore, aspects relating to infant and young child feeding practices, such as low-quality diets, limited intake of specific food categories, and infrequent and non-responsive feeding, can contribute to undernourishment and stunting.
Poor household hygiene practices and water sources contaminated by pathogens, environmental pollutants or other harmful chemicals also contribute to stunting.
Exposure to these conditions increases the risk of infections, which have been found to have an adverse effect on child development.
Severe infectious diseases, including diarrhoeal disease, respiratory illnesses such as pneumonia, malaria and intestinal worms – depending on the severity, duration and recurrence – can hinder a child's growth if there is insufficient nourishment to support recovery.
Repeated subclinical infections can cause extensive intestinal damage, thereby negatively impacting the child's ability to effectively absorb nutrients from their food and reduce the gut's ability to act as a barrier against disease-causing organisms. For example, it has been estimated that experiencing five or more episodes of diarrhoea before the age of 2 is the leading cause of stunting for 25% of affected children.
To make matters worse, poor nutrition and repeated infection feed on each other and, over time, worsen the child's nutritional status and increase its susceptibility to infectious diseases. This is because infections lead to reduced appetite, loss of energy and diminished absorption of nutrients while available nutrients are diverted from growth to the response needed to fight the infection.
Stunting is associated with an increased risk of morbidity and mortality (disease and death). The long-term effects of stunting on individuals include diminished cognitive and physical development, reduced productive capacity and poor health, and an increased risk of degenerative diseases.
Poor nutrition can severely affect the development of the brain of a foetus or newborn. Children who are stunted subsequently start education with a reduced capacity to learn and process new information.
This leads children who are stunted to score lower on tests and complete on average one year less of schooling compared to children who are not stunted.
Studies show that this impaired cognitive development, experienced in early life associated with stunting, persists in later life, and children who are stunted on average grow up to earn 20% less than people who are not stunted.
Stunting followed by excessive weight gain in later childhood increases the risk of overweight- and nutrition-related chronic diseases such as diabetes, heart disease and some forms of cancer.
For women, childhood stunting is also a direct risk factor for complications during pregnancy and delivery as well as for their baby's survival.
Children who become stunted before the age of 2 have a higher risk of poor cognitive and educational outcomes in later childhood and adolescence.
This has significant educational and economic consequences for the individual and demonstrates the link between stunting and poverty: There are direct losses in productivity due to poor physical health as a result of malnutrition, as well as indirect losses from poor functional development of the brain and less time spent in school.
In addition, affected individuals face increased health care costs for infections and chronic diseases.
Ultimately, stunting is a significant public health concern and impacts national development and comes with a high economic cost.
The World Bank estimates that a 1% loss in adult height due to childhood stunting is associated with a 1.4% loss in economic productivity.
Studies have shown that children who are stunted earn 20% less as adults compared to non-stunted individuals, and the Gross Domestic Product losses are estimated at several billion dollars per year.
Stunting has strong intergenerational links. Women who were stunted in their childhood tend to have children who are stunted, which creates an inherited and vicious cycle of poverty and reduced human capital.
Children raised in families of a low socio-economic background are often affected by early childhood stunting, as their parents might not be able to afford a high-quality diet for their child and mother or ensure optimal feeding conditions if both parents work outside the household.
Individuals who are stunted are then likely to earn less than non-stunted individuals due to suboptimal development of their cognitive capacities.
Furthermore, they often face additional health-related costs linked to infections and non-communicable diseases resulting from childhood stunting. This reinforces a cycle of poverty and stunting, which can persist for many generations.
Unfortunately, there is no "cure" for stunting, which is why efforts to tackle stunting primarily focus on prevention. However, current research explores the topic of so-called "catch-up growth" as a potential means of recovery for affected children.
Studies have observed that children who are stunted can sometimes experience sudden growth spurts for their initial height deficits.
Nevertheless, the effect of this form of sudden growth on the development and health of children and even its occurrence in the first place are subject to academic debate.
Stunting is an immense public health problem due to the sheer number of children who are stunted and the severity of its effects on people and societies.
These include both long-term effects on the individual concerning their health, their educational and economic prospects, and a negative impact of stunting on society as a whole with regard to national development and the country's economy.
This is further complicated by the fact that stunting can only be prevented, not reversed.
Most factors associated with stunting can be modified, but designing and implementing interventions to help prevent stunting remains a highly complex task.
In order to adopt measures capable of tackling stunting effectively, it is necessary to gain an extensive understanding of a multitude of factors.
Among other things, we need to consider the biological and medical aspects associated with the prevalence of stunting, the societal and environmental settings, and the organisational frameworks in which changes can be implemented.
This is where the work of the Action Against Stunting Hub comes in – read more about what we do here: https://actionagainststunting.org/