Association between duration of reproductive lifespan and Framingham risk score in postmenopausal women

The benefit of estrogen therapy in postmenopausal women is still uncertain. Based upon extensive observational data, it was believed that estrogen was cardioprotective. The relationship between the period of exposure to endogenous estrogens and the risk of cardiovascular disease (CVD) has not been studied in Korean women.

To assess associations between reproductive lifespan and CVD by using the Framingham risk score (FRS) in postmenopausal Korean women.

This cross-sectional, population-based study used data from the Korea National Health and Nutrition Examination Survey (KNHANES) for the five years 2008-2012,after adjustment for relevant variables using complex sample analysis and data weighting.

Among 25,534 women, 1973 women were enrolled, after excluding those <20 or >80 years of age (n=6194), those with diabetes, CVD or cancer (n=491), those with unrecorded physical measurements (n=7335), those with menarche age ≤8 years or ≥20 years (n=6194), and premenopausal women (n=3347).

The FRS tended to show a significant negative correlation with the reproductive lifespan (p<0.001). In multiple linear regression analysis, a negative correlation was observed between the reproductive lifespan and FRS (adjusted relative risk [RR] for <28 reproductive years [shortest lifespan group] compared with 28-33 reproductive years [moderate lifespan group], 1.2, p<0.001 and adjusted RR for >33 reproductive years [longest lifespan group] compared with 28-33 reproductive years [moderate lifespan group], -0.42, p=0.011).

A longer reproductive lifespan is associated with a lower estimated risk of CVD in the next 10 years in postmenopausal women. This result suggests that estrogen has a long-term protective effect against CVD.