Child #115181 in the Demographic and Health Survey we’re looking at is 37 months old. Let’s call the girl María. Her older brother, child #115201, is 51 months old. Let’s call him Alejandro. Despite their 13-month age difference, María plus Alejandro are both 92cm tall. María is rather short for her age – she’s at the 18 th percentile of the reference point population of well-nourished children. She’d be 96 cm if the girl were average. Alejandro is extremely brief – he’d be over 10cm taller if he were typical height for his age. He’s so short for his age, in fact , that he’s not even at the 1 st percentile. Technically Alejandro is ‘stunted’ – at ‑2. 64 their ‘height-for-age z-score’ is less than 2, meaning his height-for-age is lower than 2 standard deviations below the particular median of the reference population.
Since they’re both past their own second birthday, the chances are that María has escaped stunting yet Alejandro will stay stunted. His existence chances are much worse than their younger sister’s. Alejandro’s extreme shortness was caused by a mix of cumulative contact with infections and severe undernourishment in utero and infancy. These with each other will have affected the development not merely of his body but also associated with his brain. María will surpass him cognitive and socioemotional abilities and stay ahead. Alejandro is going to do worse at school and keep school earlier. He will earn much less in adulthood – in part because of his less developed cognitive abilities but also because of his shorter prominence. He is also at greater danger of non-communicable diseases in later on life.
The aggregate stunting income penalty
Moving beyond María and Alejandro to other stunted plus non-stunted children in their country, we can see how entire countries pay a problem – in terms of a lower per capita lower income – for not addressing stunting in early childhood. Several studies have attempted to quantify this aggregate penalty searching directly at the association between stunting and adult height, and elevation on earnings, or by using data linking stunting in early childhood to earnings in adulthood from a seminal small-scale efficacy study conducted in 4 impoverished villages in rural Guatemala.
In a plan research note that came out today, we all and our co-authors assembled the broader evidence base to re-estimate the aggregate income penalty that countries incur from childhood stunting. We calculate the effects of childhood stunting on lifetime income operating through all potential pathways: reduced education (‑1. 6 years on average), decreased height in adulthood (‑6cm on average), and lower cognitive abilities (‑0. 6 standard deviations on the typical test). For each of these paths, we translate the deficit in to the lower labor market returns – and hence lost adult income – that a stunted child incurs whenever she join the labor force.
These numbers allow us to put a number on the following believed experiment: how much higher would the country’s GDP per capita become today if none of its present workers had been stunted in childhood? The answer obviously depends in part for the prevalence of stunting when nowadays workers were children, which is dependent in part on the median age of today’s workers. In the case of Chile, the rate of stunting when today’s median-age employee was a child was just 8%. In Bangladesh, it was 70%.
We adopt a method utilized in the growth literature called ‘development accounting’ to combine these stunting rates with the income penalties in terms of education, cognition and height incurred by a worker who was stunted in childhood. We find that the average country’s GROSS DOMESTIC PRODUCT per capita is 7% lower than it would have been if none of its current workers had been stunted within childhood. In Africa and Ersus Asia, the average is even higher (9-10%).
Yet what are the returns to interventions that reduce stunting?
The potential economic benefits then of interventions to reduce stunting are sizable, even if they occur many years later on. Realizing these benefits requires surgery that reduce stunting. The more effective they are in reducing stunting as well as the cheaper they are, the larger will be their own economic returns.
There is one set of interventions for which experts have estimated both the per capita costs and the overall impacts on stunting prevalence. It is a package associated with 10 key ‘nutrition-specific’ interventions achieving pregnant women and children in the 1st 1, 000 days, starting from conception, including things like micronutrient supplements, energy protein and calcium supplements in pregnancy, nutrition education, supporting feeding, and breastfeeding promotion. Researchers estimate that if these interventions were scaled up across 34 high-stunting countries from current levels to 90%, stunting rates would fall by 20%.
This is not an especially large impact, but as seen above, even a small modify in stunting is associated with huge changes in income. Moreover, these types of interventions might have impacts on additional key child outcomes that are also part of the Sustainable Development Goals (SDGs), such as child survival, and their combined cost is not that big (less than $5 per capita).
Putting these relatively low program cost figures along with our earlier estimates of the long lasting income gains from reducing stunting, we come up with a benefit-cost ratio and a rate-of-return for this nutrition package. We factor in that the costs are sustained today while the benefits – when it comes to higher incomes – don’t kick in until the child joins the labor force in 15 or so years’ time. We also account for the fact that nations start from different coverage rates from the 10 interventions, which need to scaled up to 90% coverage. We estimate that for every dollar spent, this program achieves $15 in benefits, supposing a discount rate of 5%, and its rate-of-return is 17%.
These figures likely undervalue the social returns, as they disregard the possible benefits to society in general from having more educated workers and mothers. Our estimate continues to be reasonably high even if we make more conservative assumptions. In the ultra-pessimistic case, where we double this program cost to almost $10 for each capita, halve the program’s impact on stunting to 10%, and halve the assumed impact of stunting on education, height and cognition, we come up with a rate-of-return estimate associated with around 10%.
What else beyond direct nutrition-specific interventions?
Climbing the nutrition package up to 90% coverage – no mean task – reduces stunting by just 20%, well short of the forty percent reduction called for in the SDGs. Even if we assume on top of this the recent downward trend in stunting proceeds, we still fall short.
Fortunately, there are other weapons available. Recently there have been attempts to synthesize the evidence of the effects of these so-called ‘nutrition-sensitive’ interventions that address the underlying determinants of nutrition. They include conditional cash transfer (CCT) schemes that improve child nutrition by providing households with additional resources to purchase increasingly more nutritious food, and by encouraging growth monitoring and pre- and post-natal consultations. They include agricultural and livelihood interventions that enhance the intake of micronutrient-rich and animal-source food. Water and sanitation-related interventions, which includes infrastructure investments as well as interventions that promote behavior change like handwashing, can also help by reducing the condition environment to which children are exposed. Programs that promote better parenting, and increase early stimulation and studying, not only lower the long-term price of stunting but also increase cognitive and socioemotional development even beyond the very first two years of life.
Known knowns, and known unknowns
We all know children like Alejandro who begin life stunted will suffer an income penalty over their lives, and therefore a country’s GDP today is smaller today to the extent it failed to eliminate childhood stunting when the current workers were children. We know that even though scaling up direct nutrition interventions to 90% coverage would reduce stunting by only 20% or so, the costs are sufficiently little, and the effects on income sufficiently large, for this investment to have a healthful rate-of-return of the order of 17%. And we know that several complementary nutrition-sensitive interventions are available to help us get to the 40% stunting reduction called for by the SDGs.
What we should don’t yet know is just how much stunting would be reduced by in case each were scaled up, and how much this scaling-up would cost. A rate-of-return analysis of each of those interventions would have to factor in that each has benefits to society that move well beyond their nutrition impacts: getting children into school plus keeping them there; improving mature nutrition; reducing the cost of getting moving water; and increased cognitive and socioemotional development. Moreover, the returns to each intervention is likely to depend on the scale of the others. Not a simple exercise, then, but one that might help guide policymakers ensure that more kids start life like María and fewer like Alejandro, and avoid the large per capita income losses associated with the child years stunting.
Function Story: http://www.worldbank.org/en/news/feature/2017/03/30/well-designed-early-childhood-development-programs-can-pay-big-dividends.