Evaluation of Linear Growth at Higher Altitudes. uri icon

abstract

  • ImportanceIrrespective of their genetic makeup, children living in an ideal home environment that supports healthy growth have similar growth potential. However, whether this potential is true for children residing at higher altitudes remains unknown. ObjectiveTo investigate whether altitude is associated with increased risk of linear growth faltering and evaluate the implications associated with the use of the 2006 World Health Organization growth standards, which have not been validated for populations residing 1500 m above sea level. Design, Settings, and ParticipantsAnalysis of 133 nationally representative demographic and health cross-sectional surveys administered in 59 low- and middle-income countries using local polynomial and multivariate regression was conducted. A total of 964299 height records from 96552 clusters at altitudes ranging from -372 to 5951 m above sea level were included. Demographic and Health Surveys were conducted between 1992 and 2018. ExposuresResidence at higher altitudes, above and below 1500 m above sea level, and in ideal home environments (eg, access to safe water, sanitation, and health care). Main Outcomes and MeasuresThe primary outcome was child linear growth deficits expressed in length-for-age/height-for-age z scores (HAZ). Associations between altitude and height among all children and those residing in ideal home environments were assessed. Child growth trajectories above and below 1500 m above sea level were compared and the altitude-mediated height deficits were estimated using multivariable linear regression. ResultsIn 2010, a total of 842 million people in the global population (approximately 12%) lived 1500 m above sea level or higher, with 67% in Asia and Africa. Eleven percent of the sample was children who resided 1500 m above sea level or higher. These children were born at shorter length and remained on a lower growth trajectory than children residing in areas less than 1500 m above sea level. The negative association between altitude and HAZ was approximately linear through most part of the altitude distribution, indicating no clear threshold for an abrupt decrease in HAZ. A 1000-m above sea level increase in altitude was associated with a 0.163-unit (95% CI, -0.205 to -0.120 units) decrease in HAZ after adjusting for common risk factors using multivariable linear regressions. The HAZ distribution of children residing in ideal home environments was similar to the 2006 World Health Organization HAZ distribution, but only up to 500 m above sea level. Conclusions and RelevanceThe findings of this study suggest that residing at a higher altitude may be associated with child growth slowing even for children living in ideal home environments. Interventions addressing altitude-mediated growth restrictions during pregnancy and early childhood should be identified and implemented.
  • Key PointsQuestionDo children residing at higher altitudes have systematically different linear growth trajectories? FindingsIn this cross-sectional study including 964299 children aged 0 to 59 months, those residing at higher altitudes were, on average, born at a shorter length and remained on a lower growth trajectory than children residing at lower altitudes. This altitude-mediated growth difference remained statistically and biologically significant after controlling for potential confounding factors or when the sample was restricted to children living in ideal home environments. MeaningThe findings of this study suggest that specific attention and health care guidance are needed for the management of pregnancies and early child development in high-altitude settings; altitude-specific adjustments to 2006 World Health Organization growth standards are not recommended.
  • This cross-sectional study examines the growth trajectories of children born at higher altitudes.

publication date

  • 2020
  • 2020