Association of weight, smoking, and alcohol consumption with age at natural menopause.

In South Korea, rapid economic growth and modernization have led to changes in lifestyle factors that may affect age at natural menopause. Data from 4,793 women aged ≥55 years, who had a natural menopause, were analyzed from the Korea National Health and Nutrition Examination Survey (2013-2017). Multinomial logistic regression was used to examine the association between lifestyle factors and age at natural menopause after adjusting for birth cohort (Model 1) and sociodemographic and reproductive factors (Model 2). Overall, 3.1% of women experienced premature menopause (<40 years), 7.6% early menopause (40-44 years), and 12.8% late menopause (≥55 years). Women born in the 1940s or earlier among the birth cohorts had the highest prevalence of premature (70.0%), early (58.5%), and late (43.1%) menopause. In Model 2, current smoking (odds ratio = 3.99 and 95% confidence interval = 1.35-11.81) was associated with premature menopause. Low (<18.5 kg/m) and high (≥25 kg/m) body mass index were associated with early (odds ratio = 2.30 and 95% confidence interval = 1.01-5.22) and late (odds ratio = 1.38 and 95% confidence interval = 1.10-1.72) menopause respectively. Conversely, there was no association between age at natural menopause and alcohol consumption. The results suggest that healthy lifestyle factors, such as not smoking and proper weight maintenance, are significant factors affecting age at natural menopause. Our findings may help develop health policies and provide targeted care to improve women's health after midlife.