Social Inequalities in Height: Persisting Differences Today Depend upon Height of the Parents

Cesar V Munayco,Bruna Galobardes,Laura D Howe,George Davey Smith,Debbie A Lawlor,John Lynch,Peter Mccarron,Valerie A Mccormack

doi:10.1371/journal.pone.0029118

Abstract

BackgroundSubstantial increases in height have occurred concurrently with economic development in most populations during the last century. In high-income countries, environmental exposures that can limit genetic growth potential appear to have lessened, and variation in height by socioeconomic position may have diminished. The objective of this study is to investigate inequalities in height in a cohort of children born in the early 1990s in England, and to evaluate which factors might explain any identified inequalities.Methods and Findings12,830 children from The Avon Longitudinal Study of Parents and Children (ALSPAC), a population based cohort from birth to about 11.5 years of age, were used in this analysis. Gender- and age-specific z-scores of height at different ages were used as outcome variables. Multilevel models were used to take into account the repeated measures of height and to analyze gender- and age-specific relative changes in height from birth to 11.5 years. Maternal education was the main exposure variable used to examine socioeconomic inequalities. The roles of parental and family characteristics in explaining any observed differences between maternal education and child height were investigated.Children whose mothers had the highest education compared to those with none or a basic level of education, were 0.39 cm longer at birth (95% CI: 0.30 to 0.48). These differences persisted and at 11.5 years the height difference was 1.4 cm (95% CI: 1.07 to 1.74). Several other factors were related to offspring height, but few changed the relationship with maternal education. The one exception was mid-parental height, which fully accounted for the maternal educational differences in offspring height.ConclusionsIn a cohort of children born in the 1990s, mothers with higher education gave birth to taller boys and girls. Although height differences were small they persisted throughout childhood. Maternal and paternal height fully explained these differences.

Highlights

Height is a highly heritable trait [1]
Height differences were small they persisted throughout childhood
We have previously reported a small but clear gradient in birth length, which persists throughout childhood to mean age 10 years, across levels of maternal education in the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort, a birth cohort of children born in the 1990s in the UK [18,19]

Summary

Introduction

There is substantial variation of adult height, both in populations from different countries [2], and within a population over time, as the range in growth rates, from 10 to 30 mm/decade, across European populations demonstrate [3] This variability strongly suggests that environmental, and potentially modifiable factors, have a role in determining height [4]. Socioeconomic circumstances, overcrowding and childhood illnesses [10], dietary supplementation [11], maternal smoking during pregnancy and parental smoking in childhood [12,13,14] are all related to variations in infant and childhood height, and to attained adult height [15,16] These exposures are potentially modifiable and are differently distributed across socioeconomic groups. The objective of this study is to investigate inequalities in height in a cohort of children born in the early 1990s in England, and to evaluate which factors might explain any identified inequalities

Objectives

Methods

Results

Discussion

Conclusion