Adult stature, body proportions and age at menarche in the United States National Health and Nutrition Survey (NHANES) III

Background: Previous studies have found that age at menarche is associated with stature, primarily via leg length. However, the effects appear to vary by population and/or time period. Improving socioeconomic conditions might amplify the association. Aim: To test whether the association between early menarche and reduced stature in industrialized countries is mediated by leg length. To further test whether these effects are modified by years of education, as a proxy for socioeconomic conditions. Subjects and methods: The study used data on from 3174 21-40 year-old women who participated in the third National Health and Nutrition Survey of the US (NHANES III). The anthropometric measurements employed were stature, sitting height and upper leg length. Leg length, lower leg length and ratio of sitting height to leg length were calculated. Results: Earlier menarche was associated with shorter stature, by similar to 3.9mm per year of advancement, all of which was attributable to shorter leg length. Almost two-thirds of the effect was in the lower (distal) leg. Years of education did not significantly modify effects of pubertal timing on stature or body proportions. Conclusion: Socioeconomic conditions might not explain variable associations between linear body proportions and pubertal timing.