Association Between Reproductive Lifespan and All-Cause and Cardiovascular Mortality in Women Aged 65 Years and Older: A Cohort Study Using NHANES 1999-2018 Data.

Purpose: The association between reproductive lifespan and all-cause and cardiovascular mortality in women aged ≥65 years remains unclear. We examined this association in a nationally representative sample of older US women using NHANES data. Patients and Methods: The study included postmenopausal women aged 65 years and older from the NHANES database as our study cohort. Throughout the analyses, NHANES sampling weights were applied to account for the complex survey design, and multiple imputation were used to deal with missing values. Multivariable Cox regression, restricted cubic splines, Kaplan-Meier survival curves, and subgroup analyses were used to estimate the associations between reproductive lifespan and both all-cause and cardiovascular mortality. Additionally, sensitivity analyses were performed to verify the robustness of the results. Results: Among 4514 participants followed for a median of 101 months, all-cause mortality occurred in 1843 (38.67%) and cardiovascular mortality in 512 (10.74%). A linear relationship was observed between reproductive lifespan and all-cause mortality; in the fully adjusted model, for each additional year of reproductive lifespan, the risk of all-cause mortality decreased by 1% (HR = 0.99, 95% CI 0.98-0.99, p < 0.001). Conversely, the relationship between reproductive lifespan and cardiovascular mortality followed an L-shaped curve. Further threshold-effect analysis identified an inflection point at 36 years: for reproductive lifespan < 36 years, each additional year conferred a 2% reduction in cardiovascular mortality risk (HR = 0.98, 95% CI 0.95-1.00, p = 0.033), whereas the protective effect plateaued when reproductive lifespan ≥ 36 years. Conclusion: Short reproductive lifespan may be associated with an increased risk of all-cause and cardiovascular mortality. Greater attention should be given to women with a short reproductive lifespan.