Child growth stunting and development in Malawi

Stunting affects 159 million children under five years of age worldwide. Approximately 36% of the world’s stunted children live in sub-Saharan Africa. Stunting is a measure of chronic undernutrition, and it is associated with increased mortality, morbidity and developmental problems from early childhood onwards. This thesis is based on four studies. The aims of this thesis were to describe the timing of stunting and possible growth recovery in a rural low-income population, to examine the association between early development and later school achievements, and to examine the associations between childhood growth and later health and developmental outcomes, such as cognitive capacity and depressive symptoms in adolescence. In this Lungwena Child Survival Study (LCSS), 813 participants were followed from the fetal period until the age of 15. Their growth was regularly monitored. In addition, a developmental assessment inventory was conducted at five years of age, mathematics test at 12 years of age and pubertal stage, cognitive capacity and depressive symptoms at 15 years of age. Cognitive capacity was assessed with Raven’s Coloured Matrices score, reaction time (RT) and mathematics test, and depressive symptoms with Short Mood and Feelings Questionnaire (SMFQ). The association between development at 5 years of age and mathematics skills at 12 years, and the associations between growth and cognitive capacity and depressive symptoms at 15 years were assessed with regression models. Potential confounders were added in the models and multiple imputation (MI) was used when appropriate. Majority of the children (80%) were stunted (height-for-age < -2 SD) at two years of age, but the prevalence of stunting declined to 37% at 15 years. Most of the children who were stunted at two years, became non-stunted during the follow-up period. Only 9% of boys and 20% of girls reached advanced puberty by the end of the follow-up period at 15 years of age. Higher developmental summary score at 5 years predicted higher percentage of correctly answered mathematics questions at 12 years. Height gain between 24 months and 15 years was statistically significantly associated with Raven’s Coloured Matrices score, but not reaction time (RT) nor mathematics test. The association weakened when school education was added in the model as a potential confounder. The mean score of SMFQ in this cohort was 15. The traditional cut-off for significant depressive symptoms is 11. About 90% (95% CI 87%–92%) of the participants scored 11 or more points. Birth weight, growth, gender or pubertal maturity were not associated with SMFQ score in the primary analyses, in which the missing data was handled with multiple imputation (MI). In the sensitivity analyses with the completely observed data, birth weight was negatively and statistically significantly associated with SMFQ score. In conclusion, I suggest that catch-up growth is possible throughout the period from birth until 15 years of age. Later pubertal development may provide an opportunity for further growth in adolescence. There is an association between early development and later school achievements, and height gain in childhood has an association with cognitive capacity later on. Part of the association between growth and intelligence seems to be mediated by schooling. The prevalence of depressive symptoms in this cohort is high, and low birth weight may contribute to depressive symptoms in adolescence.