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

Abstract

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.

Fig. 1.

Adjusted population means (95% CI) for natural logarithm-transformed FSH and E2 (A), back-transformed FSH and E2 (B), rate of change for natural logarithm-transformed FSH (C) and E2 (D), and segmented mean profiles of log(FSH) and log(E2) (E), and FSH and E2 (F) across the FMP (total n = 1215). *, The y-axis is unitless for A, B, E, and F. The units of hormone are marked in the corresponding curves.

Fig. 2.

Population mean (95% CI) profiles for FSH and E2: obese vs. nonobese (A and B) and smoking vs. nonsmoking (C and D) women across the FMP. The vertical reference line is time at the FMP (total n = 1215). *, Natural logarithm-transformed FSH and E2 were used for modeling and back-transformed to original scales for data presentation.