Past oral contraceptive and hormone therapy use and endogenous hormone concentrations in postmenopausal women

Exogenous sex hormone use is associated with many health effects. Current exogenous hormone use influences endogenous sex hormone levels, but little is known about longer term effects on endogenous hormones after cessation of use. The aim of this study was to examine the relationship between past hormone use and current endogenous hormone status.

This was a cross-sectional study of 1,983 postmenopausal women aged 55 to 81 years from the general community. The women were not currently using exogenous hormones. Past use of oral contraceptives (OCs) and hormone therapy (HT) as well as circulating endogenous sex hormones and sex hormone-binding globulin concentrations were evaluated.

Past OC users had significantly lower endogenous estradiol, estrone, androstenedione, testosterone, and sex hormone-binding globulin concentrations compared with never users independent of age, body mass index, smoking, physical activity, and reproductive factors. Past HT users had significantly lower testosterone and 17alpha-hydroxyprogesterone concentrations. Past OC use and HT use were both independently associated with lower testosterone concentrations: -9% (95% CI: -16% to -2%) for ever OC use compared with never OC use and -7% (95% CI: -17% to -2%) for ever HT use compared with never HT use. The magnitude of 5% to 10% differences in endogenous hormone concentrations was similar or greater for past OC use compared with past HT use, although OC use occurred earlier in the past.

Past OC use and HT use seem to be related to long-term differences in endogenous sex hormones and sex hormone-binding globulin concentrations in postmenopausal women many years after cessation of use. These findings have implications for understanding the longer term effects of exogenous hormone exposures earlier in life with health and disease risk in later life.