Background: HIV-exposed uninfected (HEU) children experience increased mortality compared wit their HIV-unexposed uninfected (HUU) peers. It is unclear whether HEU children are also at increased risk for undernutrition, a modifiable risk factor for mortality. Methods: We conducted a cross-sectional, population-based survey of children under 5 years of age in five health districts in Botswana. Linear mixed-effects models were used to assess continuous outcomes while generalized estimating equations were used to estimate relative risks of stunting, wasting, and underweight between HEU (n=396) and HUU (n=1,109) children. Secondary analyses examined potential mediation by low birthweight. Results: The association between maternal HIV-exposure and child stunting varied significantly by child age (p<0.01). HEU children <1 year and ≥2 years of age had 1.85 (95% CI: 1.03-3.31; p=0.04) and 1.41 (95% CI: 1.06-1.88; p=0.02) times the risk of stunting compared with HUU children after multivariate adjustment, respectively. During the period of 1-2 years of age, when breastfeeding cessation occurred among HUU children, HUU children had increased risk of stunting compared with HEU children who were predominantly formula fed (RR: 1.56; 95% CI: 1.05-2.32; p=0.03). A mediation analysis estimated 67% of the excess risk of stunting among HEU children ≥2 years was attributable to low birthweight (p=0.02). There was no difference in risk of wasting or underweight. Conclusion: HEU children are at increased risk of stunting compared with their HUU peers; however, interventions to increase birthweight may significantly ameliorate this excess risk. Interventions to support optimal growth during weaning are needed for all breastfed children
