Importance: Early menarche and early menopause are associated with increased risk of cardiovascular disease (CVD) in midlife, but little is known about the association between reproductive life span and the risk of CVD.
Objective: To investigate the association between the length of reproductive life span and risk of incident CVD events, while also considering the timing of menarche and menopause.
Design, setting, and participants: Individual-level data were pooled from 12 studies participating in the International Collaboration for a Life Course Approach to Reproductive Health and Chronic Disease Events consortium. Women provided complete information on the timing of menarche and menopause, nonfatal CVD events, and covariates. Cox proportional hazards models were used to estimate hazard ratios and 95% CIs, adjusted for covariates. The association between reproductive life span and CVD was adjusted for age at menarche and age at menopause separately. Analysis began March 2018 and ended December 2019.
Exposures: Reproductive life span was calculated by subtracting age at menarche from age at menopause and categorized as younger than 30, 30 to 32, 33 to 35, 36 to 38 (reference group), 39 to 41, 42 to 44, and 45 years or older.
Main outcomes and measures: First nonfatal CVD event, including coronary heart disease and stroke events.
Results: A total of 307 855 women were included. Overall, the mean (SD) ages at menarche, menopause, and reproductive life span were 13.0 (1.5) years, 50.2 (4.4) years, and 37.2 (4.6) years, respectively. Pooled analyses showed that women with a very short reproductive life span (<30 years) were at 1.71 (95% CI, 1.58-1.84) times higher risk of incident CVD events than women with a reproductive life span of 36 to 38 years after adjustment for covariates. This association remained unchanged when adjusted for age at menarche but was attenuated to 1.26 (95% CI, 1.09-1.46) when adjusted for age at menopause. There was a significant interaction between reproductive life span and age at menarche associated with CVD risk (P < .001). Women who had both short reproductive life span (<33 years) and early menarche (age ≤11 years) had the highest risk of CVD (hazard ratio, 2.06; 95% CI, 1.76-2.41) compared with those with a reproductive life span of 36 to 38 years and menarche at age 13 years.
Conclusions and relevance: Short reproductive life span was associated with an increased risk of nonfatal CVD events in midlife, and the risk was significantly higher for women with early age at menarche.