title: Lower age at menarche affects survival in older Australian women: results from the Australian Longitudinal Study of Ageing.
abstract: BACKGROUND
  While menarche indicates the beginning of a woman's reproductive life, relatively little is known about the association between age at menarche and subsequent morbidity and mortality. We aimed to examine the effect of lower age at menarche on all-cause mortality in older Australian women over 15 years of follow-up.
  
  
  METHODS
  Data were drawn from the Australian Longitudinal Study of Ageing (n = 1,031 women aged 65-103 years). We estimated the hazard ratio (HR) associated with lower age at menarche using Cox proportional hazards models, and adjusted for a broad range of reproductive, demographic, health and lifestyle covariates.
  
  
  RESULTS
  During the follow-up period, 673 women (65%) died (average 7.3 years (SD 4.1) of follow-up for decedents). Women with menses onset < 12 years of age (10.7%; n = 106) had an increased hazard of death over the follow-up period (adjusted HR 1.28; 95%CI 0.99-1.65) compared with women who began menstruating aged >or= 12 years (89.3%; n = 883). However, when age at menarche was considered as a continuous variable, the adjusted HRs associated with the linear and quadratic terms for age at menarche were not statistically significant at a 5% level of significance (linear HR 0.76; 95%CI 0.56 - 1.04; quadratic HR 1.01; 95%CI 1.00-1.02).
  
  
  CONCLUSIONS
  Women with lower age at menarche may have reduced survival into old age. These results lend support to the known associations between earlier menarche and risk of metabolic disease in early adulthood. Strategies to minimise earlier menarche, such as promoting healthy weights and minimising family dysfunction during childhood, may also have positive longer-term effects on survival in later life.
authors.affiliation: Life course and Intergenerational Health Research Group, Robinson Institute, The University of Adelaide, Adelaide South Australia 5005, Australia. lynne.giles@adelaide.edu.au
authors.forename: Lynne C
authors.initials: LC
authors.lastname: Giles
authors.forename: Gary F V
authors.initials: GF
authors.lastname: Glonek
authors.forename: Vivienne M
authors.initials: VM
authors.lastname: Moore
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Davies
authors.forename: Mary A
authors.initials: MA
authors.lastname: Luszcz
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001315:Australia / Q000453:epidemiology; D005260:Female; D006801:Humans; D008019:Life Style; D008137:Longitudinal Studies; D008297:Male; D008572:Menarche / Q000502:physiology*; D008659:Metabolic Diseases / Q000401:mortality; D009026:Mortality; D016016:Proportional Hazards Models; D012307:Risk Factors; D016387:Women's Health