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

Background: Studying the extent to which delayed skeletal maturation may contribute to childhood height deficits is important for assessing potential for recovery in heights.

Aim: To investigate the discrepancy in height-for-age Z-scores (HAZ) based on chronological age (HAZ-19 CA) compared to bone age (HAZ-BA) and estimate proportion of HAZ deficits attributable to delayed maturation in both sexes.

Subjects and methods: 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.

Results: 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%).

Conclusion: Delayed maturation contributes to height deficits, supporting the idea that opportunity for catch-up growth continues past early childhood in both sexes.