Month of birth is associated with mortality among older people in Japan: Findings from the JAGES cohort

ABSTRACT

Month of birth (MOB) has been linked to a variety of health conditions in adulthood. This study examined the association between MOB and mortality among the healthy elderly in Japan, where a practice of traditional age reckoning was employed up until the late 1940s. The results showed male participants born in December were more likely to die earlier while those born in January had lower mortality. It is possible that social factors in early life, such as the time period when a birth is officially registered, may have implications for health that stretch across the life course.

KEYWORDS:

• Japan
• month of birth
• mortality
• season of birth

Declaration of interest

This study used data from the Japan Gerontological Evaluation Study (JAGES), conducted by the Center for Well-being and Society, Nihon Fukushi University, as one of their research projects, which was supported by the Health Labour Sciences Research Grant, Comprehensive Research on Aging and Health (H22-Choju-Shitei-008, H24-Junkanki (Syosyu)-Ippan-007, H24-Chikyukibo-Ippan-009, H24-Choju-Wakate-009, H25-Kenki-Wakate-015, H25-Choju-Ippan-003, H26-Irryo-Shitei-003 (Fukkou), H26-Choju-Ippan-006) from the Ministry of Health, Labour and Welfare, Japan; a grant from the Department of Health and Human Services; Grant-in-Aid for Scientific Research(KAKENHI) (22330172, 22390400, 23243070, 23590786, 23790710, 24390469, 24530698, 24683018, 25253052, 25870573, 25870881) from the Japan Society for the Promotion of Science; and a grant from the National Center for Geriatrics and Gerontology, Japan (24-17, 24-23, J09KF00804). NK was also supported by the CR Fixed Income Fund by AXA Life Insurance Co., LTD. These organizations do not have any conflict of interests with this study.