Socioeconomic position, lifestyle factors and age at natural menopause: a systematic review and meta-analyses of studies across six continents.
BACKGROUND
Age at natural menopause (ANM) is considered a marker of biological ageing and is increasingly recognized as a sentinel for chronic disease risk in later life. Socioeconomic position (SEP) and lifestyle factors are thought to be associated with ANM.


METHODS
We performed a systematic review and meta-analyses to determine the overall mean ANM, and the effect of SEP and lifestyle factors on ANM by calculating the weighted mean difference (WMD) and pooling adjusted hazard ratios. We explored heterogeneity using meta-regression and also included unpublished findings from the Australian Longitudinal Study on Women's Health.


RESULTS
We identified 46 studies across 24 countries. Mean ANM was 48.8 years [95% confidence interval (CI): 48.3, 49.2], with between-study heterogeneity partly explained by geographical region. ANM was lowest among African, Latin American, Asian and Middle Eastern countries and highest in Europe and Australia, followed by the USA. Education was associated with later ANM (WMD middle vs low education 0.30, 95% CI: 0.10, 0.51; high vs low education 0.64, 95% CI 0.26, 1.02). A similar dose-response relationship was also observed for occupation. Smoking was associated with a 1-year reduction of ANM (WMD: -0.91, 95% CI: -1.34, -0.48). Being overweight and moderate/high physical activity were modestly associated with later ANM, but findings were less conclusive.


CONCLUSIONS
ANM varies across populations, partly due to differences across geographical regions. SEP and some lifestyle factors are associated with ANM, but further research is needed to examine the impact of the associations between risk factors and ANM on future health outcomes.
School of Population Health, University of Queensland, Brisbane, QLD, Australia d.schoenaker@uq.edu.au.
Danielle A J M
DA
Schoenaker
School of Population Health, University of Queensland, Brisbane, QLD, Australia.
Caroline A
CA
Jackson
School of Population Health, University of Queensland, Brisbane, QLD, Australia.
Jemma V
JV
Rowlands
School of Population Health, University of Queensland, Brisbane, QLD, Australia.
Gita D
GD
Mishra
D000367:Age Factors; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008019:Life Style; D008593:Menopause; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D012959:Socioeconomic Factors; D016387:Women's Health
Menopause; body mass index; meta-analysis; physical activity; smoking; socioeconomic factors; systematic review