Child anthropometric nutritional status and anemia prevalence at extreme altitudes: evidence from the world’s highest populations

Introduction: High-altitude environments expose populations to chronic hypobaric hypoxia, which may affect maternal and child health outcomes. Although fetal growth restriction at high altitude has been widely documented, less is known about the anthropometric nutritional status and anemia patterns among children living at extreme elevations. Objective: To describe the anthropometric nutritional status and anemia prevalence among children under five years of age living at extreme altitude in the Peruvian Andes. Materials and Methods: We conducted a cross-sectional descriptive study using secondary data from the “Sistema de Información del Estado Nutricional (SIEN)”, a national nutritional surveillance system in Peru. The study included children aged 6–59 months living at an average altitude of 4,669 meters above sea level. Anthropometric indicators—height-for-age (HAZ), weight-for-height (WHZ), and weight-for-age (WAZ)—were calculated using World Health Organization (WHO) Child Growth Standards. Hemoglobin concentrations were adjusted for altitude following the 2024 WHO guidelines, and anemia prevalence was estimated using age-specific thresholds. Results: A total of 266 children were included in the anthropometric analysis. Chronic undernutrition (stunting) was observed in 18.0% of children, while 95.5% presented normal weight-for-height status. The HAZ distribution was shifted toward lower values (mean −1.25 ± 0.93), suggesting reduced linear growth in this population. Anemia analysis included 186 children aged 6–59 months. Mean altitude-corrected hemoglobin was 12.05 g/dL in children aged 6–23 months and 12.47 g/dL in those aged 24–59 months. Anemia prevalence was 4.88% and 3.88% in these groups, respectively. Conclusions: Children living at extreme altitude in the Peruvian Andes show a pattern characterized by moderate linear growth deficits but generally adequate weight-for-height indicators. After applying altitude-adjusted hemoglobin thresholds, anemia prevalence was relatively low. These findings highlight the importance of considering both environmental hypoxia and social determinants when evaluating child nutritional health in high-altitude populations.