Adolescence to Midlife Exercise Trajectories and Age at Natural Menopause: A Population Study of 246 147 Women in Norway

ABSTRACT

Objective

Lifestyle factors influence age at natural menopause, but the role of exercise remains uncertain. We aimed to identify adolescence to midlife exercise trajectories and study the associations of exercise trajectories with age at natural menopause.

Design

Retrospective population-based cohort study.

Setting

Self-administered questionnaires in the Norwegian breast cancer screening program (BreastScreen Norway) during the years 2005–2016.

Population

A total of 246 147 women, aged 50–69 years.

Methods

We used latent class mixed model analyses to identify distinct exercise trajectories from adolescence to midlife. The associations were estimated as hazard ratios using Cox proportional hazard models. Adjustments were made for year and country of birth, educational level, number of childbirths, smoking habits and body mass index. We identified four adolescence to midlife exercise trajectories: high (reference), increasing, decreasing and low exercise levels.

Main Outcome Measure

Age at natural menopause.

Results

The adjusted hazard ratio of reaching menopause was highest for women with constantly low exercise levels as compared to women with constantly high exercise levels (adjusted hazard ratio 1.06, 95% CI: 1.05–1.07). Also, decreasing and increasing exercise levels were associated with higher hazards of reaching menopause (adjusted hazard ratios 1.02; 95% CI: 1.01–1.04 and 1.02; 95% CI: 1.00–1.03, respectively).

Conclusions

Women with low exercise levels from adolescence to midlife had the earliest menopause, and women with high exercise levels had the latest. However, the associations were weak, suggesting little influence of exercise on the large variation in age at menopause.