Reproductive history in relation to plasma hormone levels in healthy post-menopausal women

Objectives: We sought to examine the relationship between reproductive hist ory and measures of selected gonadotrophins and steroid hormones among post -menopausal women. Previous studies have suggested that there is a negative correlation between parity and post-menopausal serum estrogens, which may be a mechanism by which pregnancies protect women from the development of b reast cancer. Methods: We analyzed women who experienced a natural menopaus e within the Healthy Women Study cohort both 1 and 8 years after menopause. Lifetime reproductive history was obtained and blood was assayed for estro ne, estradiol, androstenedione, testosterone, follicle stimulating hormone (FSH), and luteinizing hormone (LH) at 1 year post-menopause and for many o f these steroid hormones at 8 years post-menopause. Also at 8 years post-me nopause, a hip bone mineral density measure was obtained. Results: Age at m enopause related to a modest increase in estrone at 1 year but a decrease i n estrone and estradiol at eight years. Adjustment for body mass index (BMI ), oral contraceptive use, alcohol use, cigarette smoking, and education ha d little impact on these findings. There were no other internally consisten t relationships between reproductive variables and steroid hormones or hip- bone mineral density. Conclusions: These observations do not support the hy pothesis that parity acts to diminish endogenous levels of post-menopausal estrogens. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.