Date Published: April 18, 2019
Publisher: Public Library of Science
Author(s): Cheikh Mbacké Faye, Sharon Fonn, Jonathan Levin, Russell Kabir.
Childhood stunting is a public health concern in many low-and-middle income countries, as it is associated with both short-term and long-term negative effects on child cognitive development, physical health, and schooling outcomes. There is paucity of studies on recovery from stunting among under five children in these countries. Most studies focused on the recovery much later in adolescence. We used longitudinal data from two Nairobi urban settlements to determine the incidence of recovery from stunting and understand the factors associated with post-stunting linear growth among under-five children. A total of 1,816 children were recruited between birth and 23 months and were followed-up until they reached five years. We first looked at the time to recover from stunting using event history analysis and Cox regression. Second, we used height-for-age z-score slope modelling to estimate the change in linear growth among children who were stunted. Finally, we fitted a linear regression model of the variation in HAZ on a second degree fractional polynomials in child’s age to identify the factors associated with post-stunting linear growth. The principal findings are: i) the incidence of recovery from stunting was 45% among stunted under-five children in the two settlements; ii) timely child immunization, age at stunting, mother’s parity and household socioeconomic status are important factors associated with time to recover from stunting within the first five years of life; and iii) child illness status and age at first stunting, mother’s parity and age have a strong influence on child post-stunting linear growth. Access to child health services and increased awareness among health professionals and child caregivers, would be critical in improving child growth outcomes in the study settings. Additionally, specific maternal and reproductive health interventions targeting young mothers in the slums may be needed to reduce adolescent and young mother’s vulnerability and improve their child health outcomes.
In many low-and-middle income countries (LMICs), childhood stunting is a public health concern as it is associated with both short-term and long-term negative effects on child development including worse cognitive development, physical health, and schooling outcomes [1–3]. Also, increased child morbidity and mortality, have been reported among the consequences of child growth failures including stunting [4–8]. Definition and measurement of linear catch-up growth have been a subject of scientific debate over the last few decades. Some scholars report that linear growth retardation incurred in early childhood is persistent over time and irreversible [9–11], while more recent research argues that linear catch-up growth is possible and has been shown to occur among under-five children in studies from LMICs [12–16]. The main difference between the two arguments resides in the growth measurements and definition of catch-up growth used. In the earlier studies, absolute height gains over time were referred to as ‘catch-up growth’ which reflected a decrease in absolute height deficit between the individual child and the mean height for a reference population of healthy children (e.g. WHO child height standards). In most recent studies, catch-up in linear growth was defined in relation to changes in height-for-age z-scores which account for the increasing variability in height as children age [15, 17, 18]. Even in the latter definition, the debate continues that ‘recovery from stunting’ does not necessarily reflect ‘catch-up in linear growth’ as some children may have positive changes in height-for-age z-scores, but still remain below the reference mean. In this study, we focused on ‘recovery from stunting’ defined as a positive change in height-for-age z-scores, while recognizing that catch-up in linear growth may not have occurred for all children in that group.
We plotted the heights of children against their age to visualize the growth patterns from birth to five years comparing the overall sample to only children who were stunted. We added the WHO upper and lower height growth references to the chart in order to compare our study population with normal reference children. As shown in Fig 1, children in the study areas (either stunted or not stunted) brushed the lower boundary of the WHO height references relative to their age, reflecting persistent failure in linear growth among the under-five population.
The study used longitudinal data to explore factors associated with time to recover from stunting and identified key predictors of post-stunting linear growth among under-five children of two Nairobi informal settlements. We first used event history analysis by fitting a Cox regression model of the time to recover from stunting. Second, we used HAZ slope modeling to estimate the individual change in HAZ and fitted a fractional polynomial regression of the change in HAZ.