Abstract
Although empirical data suggest a possible link between female reproductive events and risk of nonfatal accidents and suicidal behaviors, evidence to determine these effects on mortality is scarce. This study investigated the association between female reproductive factors and the risk of external causes of death among middle-aged Japanese women. We used a population-based cohort study consisting of 71 698 women residing in 11 public health center areas across Japan between 1990 and 1994. Multivariable-adjusted Cox proportional hazard regression models were used to estimate hazard ratios (HRs) of the risk of all external causes, suicide, and accidents according to female reproductive factors at the baseline survey. During 1 028 583 person-years of follow-up for 49 279 eligible subjects (average 20.9 years), we identified 328 deaths by all injuries. Among parous women, ever versus never breastfeeding [0.67 (95% CI: 0.49–0.92)] was associated with a decreased risk of all injuries. Risk of suicide was inversely associated with ever versus never parity [0.53 (95% CI: 0.32–0.88)]. A lower risk of death by accidents was seen in ever breastfeeding [0.63 (95% CI: 0.40–0.97)] compared to never breastfeeding. This study suggests that parity and breastfeeding are associated with reduced risk of death by all external causes, suicide and/or accidents among Japanese women.
Highlights
More than five million people die each year as a result of external causes
Since female suicide completers are more likely to have a history of self-harm/suicide attempts[24], even events that occurred long before, such as menarche, may be worth considering as risk factors of their lifetime suicidality
Several variables varied by menopausal status; pre-menopausal women were younger, and reported less breastfeeding, younger age at menarche and more exogenous hormones use than post-menopausal women
Summary
More than five million people die each year as a result of external causes. These deaths have become a major public health concern[1]. Similar results were noted for deaths by accident[11,13,14,15,16] These findings remain inconsistent, and a specific mechanism to explain these associations has not been provided, except with regard to parity[12,13,17,18]. No study has comprehensively investigated reproductive factors as potential markers for mortality risk of external causes. We investigated the association between female reproductive factors and risk of all-cause and major causes of external deaths among middle-aged Japanese women
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