High altitudes linked to higher rates of stunting

Child stunting affects nearly 155 million globally, one fourth of all children under the age of five. Stunting is associated with increased risk of mortality, cognitive deficits, and metabolic developmental impairments that predispose children to chronic diseases in later life.

While stunting has multiple and complex causes, research links it closely to the standard of living and access to basic necessities such as an adequate diet and healthcare. Our new study, published in JAMA Pediatrics, suggests a significant and under-appreciated additional factor: Altitude.

Analyzing data from nearly 1 million children in 59 low- and middle-income countries, we found that children at high altitudes experience higher rates of stunting than their peers at sea level. We found this to be true even when looking just at children in “ideal home environments” where mothers were highly educated and had good health-service coverage and a high standard of living. This is the first global study of this problem that adjusts for confounding factors. While substantial gains in reducing stunting have been made over the last decade, our findings suggest that long-term efforts could falter without specific measures targeting the problem at high altitudes.

Currently, 12% of the world’s population lives at altitudes higher than 1,500 meters above sea level, largely in Asia and Africa, regions that also have high levels of child stunting. The altitude-related growth deficit emerges at birth, suggesting that the effects originate in the prenatal period. Pregnancies at high altitudes are characterized by chronic hypoxia, or an inadequate supply of oxygen, which is consistently associated with a higher risk of fetal growth restriction. This is in turn is a leading risk factor for growth faltering (or stunting) among infants and young children.

For children living in Addis Ababa, Ethiopia (~2,355 meters above sea level) the predicted height-for-age growth deficit is 0.4 standard deviations below the median child in the World Health Organization growth reference, whereas for La Paz, Bolivia (~3,650 masl) this can be as high as 0.6 SD. Such levels of stunting are significant and require sustained action to address: Remedying similar levels of growth deficit in the Gambia required four decades of intensive nutrition-sensitive and nutrition-specific interventions.

Failing to address growth faltering related to high altitude will mean keeping a significant proportion of the world population from realizing its full potential for a healthy life. It may also lead to a global failure to meet the Sustainable Development Goals (SDGs) and World Health Assembly nutrition targets. The COVID-19 pandemic, whose impacts fall disproportionately on poor and vulnerable populations, further complicates this challenge. Unless bold policy actions are taken to address its effects, according to the UN Department of Economic and Social Affairs, achieving the SDGs by 2030, including the target to reduce childhood stunting, “is likely to slip out of reach.”

To continue making progress on global stunting levels, policy makers and scientists must work together to understand what interventions are most effective to address the problems of high altitudes. Some potential solutions, such as oxygen enrichment in room air, or increasing atmospheric pressure in the home, may not be practical in low-income countries. Alternatives must be low cost, scalable across a population, and accessible in communities with limited infrastructure.

Kaleab Baye is an Associate Professor at Addis Ababa University. Kalle Hirvonen is a Senior Research Fellow with IFPRI’s Development Strategy and Governance Division, based in Addis Ababa. Emily Wu is a former IFPRI Communications Intern.

The data were compiled through Advancing Research on Nutrition and Agriculture funded by the Bill & Melinda Gates Foundation.