Epidemiological studies of the association between reproductive lifespan characteristics and risk of Type 2 diabetes and hypertension: A systematic review.

Some reproductive factors are found to be associated with metabolic outcomes in women; however, little is known about reproductive lifespan characteristics and the mutual effect of age at menarche and age at menopause on cardiovascular risk. This systematic review evaluated reproductive lifespan characteristics and describes the mutual effect of age at menarche and age at menopause on the risk of type 2 diabetes (T2DM) and hypertension at midlife. PubMed, EMBASE, and Web of Science were screened for studies published up to September 1, 2020. The individual effect estimates were reviewed and synthesized without meta-analysis due to methodological and clinical or conceptual diversity in reported studies. Of the 3033 identified studies, 20 were included in the final synthesis: 6 reported reproductive life span; 12 reported age at menarche, and 7 reported age at menopause. Synthesis of two cohorts, with a median follow-up of 9-11 years, showed that a shorter reproductive lifespan was positively associated with T2DM, yielding 6-15% higher risk of T2DM for a one-year decrease in reproductive lifespan. A few studies also demonstrated that women who experienced early menarche (four of six studies) and early menopause (two of five studies) were positively associated with risk of T2DM. The association between reproductive lifespan and hypertension was unclear due to the limited availability of studies. Our findings suggest that a shorter reproductive lifespan is associated with T2DM risk in postmenopausal women, especially those with early menarche and early menopause. Large cohort studies are needed to assess the association between reproductive lifespan and incident hypertension in midlife.