Delayed skeletal maturation is a major contributor to child height deficits in a low-income setting

Studying the extent to which delayed skeletal maturation may contribute to childhood height deficits is important for assessing potential for recovery in heights. To investigate the discrepancy in height-for-age Z-scores (HAZ) based on chronological age (HAZ-CA) compared to bone age (HAZ-BA) and estimate proportion of HAZ deficits attributable to delayed maturation in both sexes. Using the WHO Growth References, HAZ-CA and HAZ-BA were calculated for Guatemala City children aged 6–8.99 years participating in the Universidad del Valle de Guatemala Longitudinal Study and attending a low or a very low SEP study school. A mixed effects model was developed to describe 1638 HAZ observations (Level 1) in 1107 children (Level 2) by HAZ-type, with interaction terms for HAZ-type by age, sex, school, and birth year. On average, skeletal age was delayed by 1.1 (SD 1.0) years. Mean HAZ-CA was −1.7 (0.9) and HAZ-BA −0.6 (0.9). Greater proportions of the total height deficit were attributable to delayed skeletal maturation in males (60-87%) versus females (49–63%), and at low- (58–87%) versus very low-SES school (49–71%). Delayed maturation contributes to height deficits, supporting the idea that opportunity for catch-up growth continues past early childhood in both sexes.