The consequence of birth spacing for first- and second-born siblings’ long-term income rank: A restrictive two-child family approach

Roujman Shahbazian

doi:10.20377/jfr-159

Abstract

Birth spacing between siblings may have long-lasting impacts on them. This paper focuses on how different birth-spacing intervals are associated with income rank during the ages 33 to 42 years. In order to disentangle birth spacing from birth order, while holding potential sibsize association constant, an interaction model is used on a restrictive subpopulation of two-child families born between 1960 and 1970. The results show clear differences between first- and second-born siblings. Increased birth spacing, up to 3 years, is positively associated with first-born siblings’ income rank. Birth spacing has a negligible association with second-born siblings, at the common spacing intervals (less than 5 years). Having relatively high spacing intervals (over 5 years) is associated with somewhat lower income-rank than having mid-length intervals for both first- and second-born siblings.

Highlights

There are some circumstances beyond children’s control that impact their ability to influence their life chances, influencing equality of opportunity
All analyses are performed by OLS regressions and the reference category is second-born siblings with birth spacing below 19 months
The paper adopts a restrictive two-child-family strategy in order to analyse the association between birth spacing and first- and second-born siblings’ long-run income rank, which can be viewed as the ultimate indicator for socio-economic standing in the labour market

Summary

Introduction

There are some circumstances beyond children’s control that impact their ability to influence their life chances, influencing equality of opportunity. Scholars have criticized previous birth order studies for not using longitudinal data or for using nonrepresentative samples: see Barclay (2014) for an overview. Another less-studied characteristic of family structure argued to impact siblings’ socioeconomic outcomes is birth spacing: that is, the age difference between siblings (cf Steelman et al 2002). The few existing studies on this subject focus on the association between birth spacing and early childhood test scores (Buckles & Munnich 2012), between birth spacing and educational achievement (Powell & Steelman 1993; Pettersson & Skogman 2009), between birth spacing and sibling correlation in education and earnings (Conley & Glauber 2008) or for outcomes for three or more sibling groups (Barclay & Kolk 2017)

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Conclusion