BackgroundDoes preschool height predict adult stature in undernourished settings? The extent to which preschool length or height forecasts young adult stature is unclear in chronically undernourished populations.MethodsIn 2006-8, we assessed height in a cohort of 2074 young adults, aged 16–23 years, in rural Nepal who, as preschoolers (≤ 4 year), were measured at baseline and again 16 months later during a vitamin A supplementation trial in 1989-91. We assessed by linear regression the ability of preschool length (L, measured < 24 mo) or height (Ht, 24–59 mo), at each year of age to predict 16–23 year old height, adjusted for month of young adult age, interval duration (in months), caste, preschool weight-for-height z-score and, in young women, time since menarche, marriage status and pregnancy history.ResultsYoung women were a mean of 0.81, 1.11, 0.82, 0.24, 0.44 cm taller (all p < 0.01) and young men, 0.84, 1.18, 0.74, 0.64 and 0.48 cm taller (all p < 0.001) per cm of attained L/Ht at each successive preschool year of age and, overall, were 2.04 and 2.40 cm taller for each unit increase in preschool L/Ht z-score (L/HAZ) (both p < 0.001). Coefficients were generally larger for 16-month follow-up measurements. The percent of young adult height attained by children with normal L/HAZ (>-1) increased from 38–40% mid-infancy to ∼ 69–74% by 6 years of age. By 3–6 years of age heights of stunted children (L/HAZ<-2) were consistently ∼ 4–7% lower in their young adult height versus normal statured children. There was no effect of preschool vitamin A receipt.ConclusionsShorter young children become shorter adults but predictive effects can vary by sex, age assessed, and may be influenced by year or season of measurement.