U-shaped association between age at first childbirth and mortality: A prospective cohort study.

OBJECTIVES: We examined the association between maternal age at first childbirth and death from cardiovascular disease and all-cause mortality in Korean women. METHODS: We used data from a community-based cohort with a follow-up of 18 years (2001-2018). Participants were subdivided into three groups according to the tertiles of age at first childbirth [≤ 23 (n=1498), 24 and 25 (n=1033), and ≥ 26 years (n=1513)]. Kaplan-Meier survival analysis was performed to assess CVD mortality rates and all-cause mortality rates. We compared mortality hazard ratios (HRs) using the Cox proportional hazards model and investigated whether hypertension and diabetes mellitus (DM) affected this association using mediation analysis. RESULTS: Participants' mean ages at first childbirth and at survey entry were 24.7 and 52.4 years, respectively. Age at first childbirth and mortality (CVD and all-cause) showed a U-shaped association. Compared with the group aged 24 and 25 years at first childbirth, the adjusted HRs were significantly higher in the younger and older groups. Hypertension and DM did not mediate the association between maternal age at first childbirth and CVD and all-cause mortality rates. CONCLUSION: Mothers who had given birth at an early or late age were at greater risk of CVD and all-cause mortality than mothers who had given birth in their mid-20 s. We suggest that further research is needed to determine whether maternal age at first childbirth affects women's health and lifespan.

Associations among working hours, sleep duration, self-rated health, and health-related quality of life in Korean men.

BACKGROUND: This study aimed to examine the relationship between working hours and health-related quality of life (HRQOL) in men and to determine whether this relationship was mediated by sleep duration and self-rated health (SRH). MATERIALS AND METHODS: Our study population included 2141 working men aged 20 to 49 years old from the Korea National Health and Nutrition Examination Survey 2016-2017. Working hours, SRH, and HRQOL were measured by a structured questionnaire survey. Sleep duration was calculated based on self-reported data. We investigated the association between working hours and HRQOL and performed a mediation analysis to evaluate the contributions of sleep duration and poor SRH to this relationship. RESULTS: This study identified a significant association between working hours and HRQOL. Long working hours directly and indirectly affected HRQOL through poor SRH. Men who overworked were more likely to report poor HRQOL due to worsened SRH. Poor SRH was responsible for 26.3% of this relationship. But sleep duration did not explain the relationship between working hours and HRQOL. CONCLUSIONS: Working hours were directly associated with HRQOL in men. Furthermore, there was an indirect effect of working hours on HRQOL mediated by poorer SRH. An improved work-life balance is necessary to promote men's health and quality of life.