Associations of linear growth trajectories from 0-5 years with cognitive function and school achievement at 10 years of age: the Ethiopian Infant Anthropometry and Body Composition birth cohort study

This study aimed to identify linear growth trajectories from 0-5 years and assess their associations with cognitive function and school achievement in Ethiopian children aged 10 years. Latent class trajectory modelling was used to identify distinct height-for-age (HAZ) trajectories. Cognitive function was assessed using the Peabody Picture Vocabulary Test (PPVT), while school achievement was measured by Math, English, and Science (MES) combined scores and grade-for-age. Associations were assessed using multiple linear or logistic regressions. We identified 4 distinct HAZ trajectories. Decreasing trajectory (n=145, 31.9%) started high at birth but dropped sharply. The increasing-decreasing trajectory (n=196, 43.2%) increased up to 3 months followed by a decrease. The stable low (n=74, 16.3%) had low HAZ at birth, followed by a slight decrease. The rising trajectory (n=39, 8.6%) started low but then increased to HAZ above, yet close to zero. At 10 years, children in the rising trajectory had 4.54 (95% CI: -0.45, 9.55, p=0.075) higher MES combined score and 2.4 times (95% CI: 1.12, 5.15, p=0.025) higher odds of being in the appropriate grade-for-age compared to those in the increasing-decreasing trajectory. The association between stable low and decreasing trajectory with appropriate grade-for-age had odds ratio close to null. In conclusion, we found that three of the four linear growth trajectory classes showed a declining pattern. Data suggest that greater linear growth in early childhood may be associated with higher school achievement and better cognitive function.