Stunting at 24 Months and Incidence of Overweight and Obesity from Childhood to Young‐adulthood in an Urban South African Birth Cohort
Authors: Hanson Sara , Munthali Richard J. , Lundeen Elizabeth A. , Norris Shane A. , Stein Aryeh D. 
Published: November 2023

BackgroundData from several low and middle‐income countries suggest that linear growth failure, or stunting, in early childhood is related to increased risk of obesity. However, there is a growing body of literature that suggests in some countries there is a null or negative relationship. Previous studies have only looked at the relationship between stunting and obesity incidence through mid‐childhood. The present study extended the follow‐up period and examined the relationship between stunting and age‐specific patterns of overweight and obesity incidence from early childhood to young‐adulthood in the context of a country that has already gone through the Nutrition Transition.MethodsWe analyzed data from 895 participants in the Birth‐to‐Twenty study, an urban South African birth cohort initiated in 1990. Anthropometric data were collected at multiple ages and participants were included if they provided at least one measure of body mass index (BMI: kg/m2) in each of the following time periods: 4–8 years, 11–12 years, 13–15 years, 16–18 years and 22–24 years. We defined stunting at age 24 months as HAZ<−2 and overweight as BMIZ >1 for the childhood and adolescent time points and BMI>25 in adulthood. We calculated age prevalence and period incidence, and compared incidence density rates across genders and stunting status.ResultsOur sample was 93% black and 51% female. 26% of males and 19% of females were stunted at 24 months. In males, 19% were overweight or obese at 4–8 years, 13% at 11–12 years, 12% at 13–15 years, 8% at 16–18 years and 15% at 22–24 years. In females, 15% were overweight or obese at 1–2 years, 19% at 4–8 years, 24% at 13–15 years, 26% at 16–18 years and 47% at 22–24 years. Males who were stunted at 24 months had lower prevalence of overweight and obesity from 4–8 years to 16–18 years but higher prevalence of overweight and obesity at 22–24 years when compared to males who were not stunted at 24 months. Females who were stunted at 24 months had lower prevalence of overweight and obesity at all time points when compared females who were not stunted. Among males, period incidence of overweight and obesity was highest from 16–18 to 22–24 years in both those who were stunted and not stunted at 24 months. In females, period incidence was highest between 11–12 years and 13–15 years in both those who were stunted and not stunted at 24 months. The incidence density ratios (IDR) comparing incidence rates of overweight and obesity in stunted and not stunted males were 0.8 (95% CI: 0.3, 2.0) from 4–8 years to 11–12 years, 2.3 (95% CI: 0.6, 9.2) from 13–15 to 16–18 years and 1.6 (95% CI: 0.8, 3.0) from 16–18 to 22–24 years. No stunted males became overweight or obese from 11–2 years to 13–15 years so we were unable to calculate an IDR for this time period. The IDRs comparing overweight and obesity incidence rates in stunted and non‐stunted females were 0.9 (95% CI: 0.4, 1.7) from 4–8 years to 11–12 years, 0.8 (95% CI: 0.3, 1.8) from 11–12 years to 13–15 years, 1.2 (95% CI: 0.5, 2.7) from 13–15 years to 16–18 years and 0.8 (95% CI: 0.5, 1.4) from 16–18 years to 22–24 years. Incidence density rate in any time period did not differ at p<0.05 by stunting status at 24 months in either males or females.ConclusionStunting at 24 months was not related to the risk of overweight or obesity in this urban South African cohort. This suggests that stunting may not be an important contributor to the rising obesity rates in urban South Africa.Support or Funding InformationThis project was supported by NIH Research Training Grant # R25 TW009337, funded by the Fogarty International Center and the National Institute of Mental Health.