The Effect of Birth Spacing on Child Mortality in Sweden, 1878–1926

Joseph Molitoris

doi:10.1111/padr.12050

Abstract

A negative association between interval length and infant and child mortality has been consistently identified in modern developing countries. The reasons for this association are unclear, however. Leading hypotheses explain these differences as a result of sibling competition, maternal depletion, infection transmission, or unobserved maternal factors, but none has received overwhelming support. Using data from Stockholm between 1878 and 1926, this study contributes to the body of research by identifying trends in the relationship over time, controlling for unobserved maternal heterogeneity, and exploiting sibling deaths to better understand the mechanisms at work. Results show the association disappeared over time as infectious disease mortality fell and that deaths of previous siblings during the postnatal period disproportionately tended to increase the risk of dying among index children born after short intervals. These findings strongly suggest the relationship is related to the transmission of disease between closely spaced siblings. (Less)

Highlights

IntroductionI examine within-family variation in the association between preceding birth intervals and infant and child mortality risks of index children to remove the potential for the relationship to be driven purely by compositional differences across mothers
Related hypotheses argue that short intervals do not allow women’s bodies to fully recover from their previous birth in other ways, such as by depleting folate stores or by decreasing muscle tone in reproductive tissues (Conde-Agudelo et al 2012; Smits and Essed 2001)
Findings from developing countries have shown that overlapping periods of pregnancy and breastfeeding are not uncommon during short birth intervals (Boerma and Bicego 1992), which may lead to lower quality or quantity of breastmilk for the child born at the end of the interval and diminished neonatal growth (Marquis et al 2002; Marquis et al 2003)

Summary

Introduction

I examine within-family variation in the association between preceding birth intervals and infant and child mortality risks of index children to remove the potential for the relationship to be driven purely by compositional differences across mothers. I investigate the relationship between birth spacing and infant and child mortality using historical data (see Knodel and Hermalin 1984; Nault, Desjardins, and Légaré 1990; Pebley, Hermalin, and Knodel 1991); mine is the first study to examine how this relationship evolved over a roughly 50-year period of major economic and demographic changes This is a significant advantage as historical populations tended to have birth spacing patterns similar to those in contemporary developing contexts, yet had greater numbers of deaths at young ages, which can greatly improve the power of statistical analyses and aid in the search for causal mechanisms. Competition for the quality and quantity of calories obtained from food would obviously be more relevant, though it would be more a function of family size than short intervals per se

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Discussion

Conclusion