The effect of birth month on body height of Austrian conscripts varies according to educational level.

Abstract

An association between birth month and height has been repeatedly described, but no consistent seasonal patterns can be observed. In this study, the significance of educational level as a modulating cofactor for the association between body height and birth month was analysed using an anonymous data set from 1,179,600 male conscripts born in Austria between 1971 and 2002. A distinct seasonal trend was observed. Conscripts born from June to December had shorter final body height than their counterparts born between January and May. In general, the effect of month of birth on final body height is very small. Considering socioeconomic co-factors, however, this effect was particularly noticeable for the highest and middle education classes, while the observed effect was small among the lowest education class. A low educational level seems to reduce the seasonal effect on growth and finally body height. Consequently, a clear seasonal effect in body height was observed in this Austrian population-based sample, socioeconomic stress factors, such as a low level of education, can reduce the seasonal effects.