Reproductive history and cardiovascular disease risk in postmenopausal women: a review of the literature.

OBJECTIVES: It is widely believed that oestrogen protects postmenopausal women from cardiovascular disease. It is unknown, however, whether reproductive history, which affects endogenous oestrogen levels during a woman's life, also influences cardiovascular disease risk in postmenopausal women. We present an overview of the studies which investigate the relationship between reproductive history and risk for cardiovascular disease in women.
METHODS: We conducted a Medline search of literature pertaining to age at menarche, age at menopause, parity and gravidity, breast-feeding, and length and regularity of the menstrual cycle in relation to cardiovascular diseases. Data extraction and synthesis were performed by comparing odds ratios and relative risks presented or calculated.
RESULTS: Age at menarche was not found to influence cardiovascular disease risk, while menstrual cycle irregularity was associated with this risk. The studies pertaining to parity presented conflicting results: protection against as well as an increase in the risk of cardiovascular disease were found in parous women. Pregnancy loss appeared to be related to cardiovascular disease risk. Age at menopause proved to be the reproductive factor most clearly related to cardiovascular disease risk.
CONCLUSIONS: Only menstrual cycle irregularity, pregnancy losses, and age at menopause are possibly related to cardiovascular disease risk in postmenopausal women. All reproductive factors need to be studied together in order to assess reproductive history in a proper manner. Research of this kind will be essential if we are to further increase our knowledge regarding the nature of the effects of endogenous oestrogen on cardiovascular disease.