Health outcomes of only children across the life course: an investigation using Swedish register data
Population Studies (2021), accepted
Only children – children with no full biological siblings – are a growing subgroup in many high-income settings, but we know little about their life course health outcomes. We address this research gap using Swedish population register data for cohorts born 1940-1975 and introducing conceptual and methodological innovations to the literature. We compare the health of only children with children from multi-child sibling groups, taking into account birth order, family size and the presence of half-siblings. Only children had lower height and fitness scores, were more likely to be overweight or obese in late adolescence, and had higher mortality, than those with 1 or 2 siblings. However, only children without half-siblings were always healthier than those with half-siblings, suggesting that parental disruption confers additional disadvantages. The health disadvantage was attenuated but not fully explained by adjustment for parental characteristics and after employing within-family maternal cousin comparison designs.
Keywords: Sweden, adult mortality, family size, health, only child