Stunting: causes, consequences, trends and treatments

MARKO KERAC: So in this step, we’re talking about stunting. Causes, consequences, trends, and treatments. So what is stunting? Simply put, it’s a failure to reach linear growth potential. And it’s illustrated nicely in this diagram. So we see the youngest child, he’s obvious, and we assume that the oldest one is the tallest one. But in fact the oldest one is this girl. She’s too short for her age. She’s not reached her growth potential.

So how do we define it? It’s a low length or height for age. In young children under two, we measure the recumbent length. In older ones, we look at the standing height. So defining stunting. Then we compare that to a sex and age matched reference population. And these days we’re fortunate to have the WHO growth standards, which set a gold standard of how children should grow, given the optimal environmental, health, and nutritional conditions. And we interpret that. So stunting is when the child is below two standard deviations, or z-scores, of the reference population median.

Severe stunting is when they’re less than three, length or height for age, z-scores from the median, and moderate is when their below minus three to minus two z-scores from the median.

So how that works in practise. Let’s look at this growth chart for a girl. And on the x-axis, we see her age, in years and months, and on the y-axis, her height in centimetres. We can see the lines. In the middle, in the green, is the median. And the extremes are plus two and minus two z-scores and plus three and minus three. You can see she starts off just below the median, but growing well, growing roughly in parallel to the line. Sometime, between the age of three and four, we can see there’s a problem. That could be a problem at home, nutritional intake has gone down, could be an illness, could be many things. She’s dropping off, she’s becoming stunted.

That’s a process of becoming stunted.

And then eventually, if things don’t improve, she’ll become stunted. So that’s the state outcome of being stunted so we can see that above four years, she’s now below minus two. And it’s really important to distinguish those two phases, the process of becoming stunted and the stuntedness, the state of being stunted. So how many are affected? It’s important to say stunting is commonest form of malnutrition. Globally, 165 million children aged under five are affected. And unsurprisingly, it’s commonest in low and middle income countries, where 160 million of the 165 million reside.

There’s unequal distribution around the world. So Africa has the highest proportion of children stunted, at 36% and that accounts for 56 million stunted. Asia, with a larger population, has a lower proportion stunted, 27%, but 96 million in total affected. So what are the consequences? The WHO stunting policy brief summarises stunting as being one of the most significant impediments of human development, and it has short and long term consequences. Short term, there’s increased risk of morbidity, increased risk of mortality. In the latest Lancet series, stunting is estimated to account for over one million under five child deaths per year. That’s 15% of all deaths in under five children. There are developmental implications, so poorer cognitive, motor, and language development. Economic implications.

So there’s greater health expenditure for sick, for vulnerable children. Their opportunity costs for families, for carers, caring for the sick child. There are important long term consequences too. So for health, starting off with decreased adult stature, there’s increased risk for obesity and the many associated comorbidities. There’s poorer reproductive health. Development is affected, so there’s poorer school performance. Learning capacities impaired. There’s unachieved potential. And finally economic capacity, so poorer capacity to work, poorer productivity at work. And all of which clearly have huge, huge implications for low and middle income countries. So this has consequences across the life cycle.

So if we start off with a baby whose low birth weight, which itself is type in-utero malnutrition, that baby has a higher risk of mortality. It’s the early days when the brain is developing the fastest, so there’s great risk of impaired mental development. Again, there’s increasing body of evidence, the Barker hypothesis, or developmental origin of adult disease, that what happens early in-utero sets the scene for later adult life, makes epigenetic changes, influences a child’s later capacity, and risk of adult chronic disease. So that small baby, if there’s inadequate catch up growth, can grow up to be a stunted child. If there was inadequate complimentary feeding, if the child had frequent infections, if there’s inadequate food, health, and care.

And that stunted child, they have reduced physical mental capacity. If the inadequate food, health, and care continue, it’s very easy to grow to be a stunted adolescent. With again reduced physical cognitive capacity. And in turn, a stunted adult. And this has particular implications for women, whose capacity then to bear healthy, fit, normal birth weight children is impaired. So in summary, there are implications for individuals, for families, for communities, and ultimately for whole societies. But with the life cycle, there are also life cycle opportunities. And the most important are around the first 1000 days of life. So from conception to the first two years of life. And this is known as the first 1,000 days window of opportunity.

And it’s a time that the body is particularly sensitive to change, that there’s great opportunity to make a difference to impact what happens. Not just then in early life, but throughout life. So the first 1,000 days really matters. But some exciting research again about, is there a second window of opportunity in adolescence, the second period of rapid growth. Can we be doing more there to impact and to improve adult health? And finally, it’s important to not forget about supporting mothers especially, and vulnerable adults. Some really exciting and interesting research about mental health in women, for example, and how that influences their child’s nutritional stasis. So opportunities throughout the life cycle. So what are the solutions to stunting?

Ultimately, we need to address the causes and these are many. And they start with community and societal factors. The contextual causes. For example, the political economy, food prices, trade policies, marketing regulations. There’s health and health care. For example, are people able to access it? What are the availability of health care supplies like? Are there enough qualified health care providers? There’s education. Are children able to access quality education? Is there good enough infrastructure? Society and culture. Beliefs, norms, social support networks, these all make a difference. There’s agriculture and food systems, things like food processing, availability of micro nutrient rich foods, and food safety, as well as food quality. And finally, under context, is water sanitation and environment.

Then there are immediate causes, and these range from household and family causes, to complimentary feeding. For example, is the quality of food good, what about the practises, are they adequate or inadequate, what’s the food and water safety like? Breastfeeding, another vital factor. Inadequate breastfeeding counts for much child mortality and has a key role to play. And there’s infection. And all of these combined together to produce stunted growth and development. So how do we address them? Two ways of thinking about this. There are nutrition specific interventions, which are addressing complimentary feeding and breastfeeding in particular. But there’s also a much wider and more complex range of nutrition sensitive interventions.

And these cover the context, especially cover household and family factors, cover infection, nutrition-sensitive interventions. And finally, what’s happening at global level. There’s currently an exciting movement scaling up nutrition. And this is a global initiative, bringing together and mobilizing key stakeholders around four key processes to tackle malnutrition. And focusing particularly on stunting. And focusing particularly on those sensitive first 1,000 days of life. The first of those processes is about creating political and operational platforms. So strong in-country leadership. Shared stakeholder spaces, where people and organisations are coming together and taking joint responsibility for scaling up nutrition. There’s incorporating best practises into nutritional policies. Scaling up proven interventions, including the adoption of effective laws and policies.

Thirdly, it’s about aligning many different sectors, many different actions, that are needed to produce results. Having agreed results framework, having mutual accountability. And finally, it’s about increasing resources, and monitoring implementation, monitoring that progress to ultimate success. So to end. It’s important. It’s vital to have an agenda to end stunting. Children need to thrive, as well as survive. Only by tackling stunting can they achieve their full physical, cognitive, and social potential.