Birth order and height development in early childhood: empirical evidence for twenty-first-century Flanders

Abstract

Height is generally accepted as an indicator of well-being and the development of children in early childhood. Historical research shows a negative association between the height of individuals and their birth order. This is frequently explained by the resource dilution hypothesis. However, we question the negative effect of birth order on growth patterns in contemporary Flanders, where the fertility decline has stabilized and policies supporting the family are well established. Therefore, the first aim of this study is to examine the influence of birth order on early child development – in terms of height – in contemporary society. In addition, we control for socioeconomic and sociodemographic parameters. We use a longitudinal dataset of almost all births in Flanders between 2006 and 2009 (N = 291,230), together with check-ups (N = 2,949,169). All height measurements are standardized to conform to the international World Health Organization growth standards. Several statistical techniques are used to estimate a six-step model. Results show that the effects of birth order are significant at the 5% level, but explain very little of the variation in height increase. This contribution improves the understanding of the present-day link between birth order and early child development in contemporary Flanders. In light of historical trends, our results indicate that the effect of birth order is consistent but particularly small during the first three years of early childhood. Part of the explanation for the changing role of birth order at the macro level can be found in the fertility decline, the general improvement in standards of living and the development of the welfare state.

Keywords:

• Early child development
• anthropometry
• birth order
• resource dilution
• Flanders

Notes

1. To estimate the standard deviations scores (z-scores) of the anthropometric variables the formula: SDS = [(Measurement/M)^L –1) / (L × S)] was used. In this formula M represents the median, L the power to remove skewness, and S the coefficient of variation (Brannsether, Eide, Roelants, Bjerknes, & Júlíusson, 2014).