Change in follicle-stimulating hormone and estradiol across the menopausal transition: effect of age at the final menstrual period.

BACKGROUND AND
OBJECTIVE: To determine whether patterns of change in serum estradiol (E2) and FSH across the menopausal transition were associated with age at the final menstrual period (FMP). DESIGN AND
SETTING: The Study of Women's Health Across the Nation (SWAN) is a seven-site, multiethnic, longitudinal study of the menopausal transition being conducted in 3302 menstruating women who were aged 42-52 yr at the 1996 study baseline. MEASUREMENTS: Annually collected serum was assayed for E2 and FSH levels. Patterns of hormone change were evaluated in the 1215 women with a documented natural FMP by follow-up visit 9 (2006) using semiparametric stochastic and piecewise linear mixed modeling.
RESULTS: The FSH pattern across the menopausal transition began with an increase 6.10 yr before the FMP, an acceleration 2.05 yr before the FMP, deceleration beginning 0.20 yr before the FMP, and attainment of stable levels 2.00 yr after the FMP, independent of age at the FMP, race/ethnicity, or smoking status. Obesity attenuated the FSH rise and delayed the initial increase to 5.45 yr before the FMP. The mean E2 concentration did not change until 2.03 yr before the FMP when it began decreasing, achieving maximal rate of change at the FMP, then decelerating to achieve stability 2.17 yr after the FMP. Obesity, smoking behavior, and being Chinese or Japanese were associated with some variation in E2 levels but not the pattern of E2 change.
CONCLUSIONS: Time spans and overall patterns of change in serum FSH and E2 across the menopausal transition were not related to age at FMP or smoking, whereas time spans but not overall patterns were related to obesity and race/ethnicity.