Background Although sons are thought to impose greater physiological costs on mothers than daughters, sons may be advantageous for parental survival in some social contexts. The authors examined the relationship between the sex composition of offspring and parental survival in contemporary China and Taiwan. Because of the importance of sons for the provision of support to elderly parents in these populations, the authors hypothesised that sons would have a beneficial effect on parental survival relative to daughters.
Methods The authors used data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) and the Taiwan Longitudinal Study of Aging (TLSA). The CLHLS sample consisted of 4132 individuals aged 65 years and over in 2002. The TLSA sample comprised two cohorts: 3409 persons aged 60 years and over in 1989 and 2193 persons aged 50–66 years in 1996. These cohorts were followed up for 3, 18 and 11 years, respectively. The Cox proportional hazards model was used to estimate the relationship between the sex composition of offspring and parental mortality.
Results Based on seven measures of sex composition, no protective effect of sons was found in either China or Taiwan. For example, in the 1989 Taiwan sample, the hazard ratio (HR) for maternal mortality associated with having an eldest son was 0.979 (95% CI 0.863 to 1.111). In Taiwan, daughters may have been more beneficial than sons in reducing mortality in recent years.
Conclusion The authors offer several explanations for these findings, including possible benefits associated with emotional and interpersonal forms of support provided by daughters and negative impacts of conflicts arising between parents and resident daughters-in-law.
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Funding This research was supported by the Demography and Epidemiology Unit of the Behavioral and Social Research Program of the National Institute on Aging (R01AG16790); the Eunice Kennedy Shriver National Institute of Child Health and Human Development (R24HD047879) and Demography Training at Princeton University (T32HD007163). We thank Mathew Creighton, Dana Glei and Germán Rodríguez for their helpful suggestions, and Dan Plechaty for excellent research assistance. Data for this research were provided by the ‘Chinese Longitudinal Healthy Longevity Survey’ (CLHLS) managed by the Center for Healthy Aging and Family Studies, Peking University. CLHLS is supported by funds from Duke University under an award from the National Institutes on Aging (R01 AG23627-01; PI: Zeng Yi), and by the China Natural Science Foundation, the China Social Science Foundation, UNFPA and the Hong Kong Research Grant Council.
Competing interests None.
Ethics approval This study was conducted with the approval of the Institutional Review Board for Human Subjects at Princeton University (exempt).
Provenance and peer review Not commissioned; externally peer reviewed.
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