ABSTRACT: The start of the menopausal transition in most women is marked by irregularity of the menstrual cycle. Irregularity appears to correspond to changes in estrogen and follicle-stimulating hormone (FSH) levels. Variations in the pattern of change in the trajectories of estradiol (E2) and FSH during the menopause transition have not been defined well.
The Study of Women’s Health Across the Nation (SWAN) is a large multicenter, multiethnic longitudinal study of the menopausal transition. These investigators used data from SWAN to determine whether different trajectories of E2 and FSH could be identified and whether the different trajectories were related to body mass index (BMI) and race/ethnicity. The study population included 1316 postmenopausal women aged 42 to 52 years who had at least 12 months of amenorrhea not due to surgical removal of uterus and/or both ovaries or no exposure to hormone therapy before the final menstrual period (FMP). All participants were seen at 7 sites and had up to 11 annual visits for measurement of serum E2 and FSH levels. The study sample was composed of white women (42.5%); racial/ethnic groups included African Americans (31.4%), Chinese (10.0%), Japanese (10.7%), and Hispanics (5.4%). At baseline, 32.1% of women were obese. Primary study outcome measures were the annual serum E2 and FSH levels anchored to the FMP.
Four distinct E2 trajectories across the FMP were identified: slow decline (26.9% of the sample), flat (28.6%), rise/slow decline (13.1%), and rise/steep decline (31.5%).
Three FSH trajectories across the FMP were identified: low (10.6%), medium (48.7%), and high (40.7%) rising patterns. Body mass index and race/ethnicity were related significantly to the E2 and FSH trajectories (P < 0.0001). The data showed that obese women in all race/ethnic groups followed a flat E2 and low FSH trajectory. Moreover, women who exhibited the rise/steep decline E2 and high FSH trajectories tended to be normal-weight white and African American, whereas women exhibiting the slow decline E2 and the high/medium FSH trajectories tended to be normal-weight Chinese /Japanese.
These findings show that changes in E2 and FSH trajectories occurring over the menopausal transition are not uniform across this study population. The differing hormone trajectories during the menopausal transition were strongly related to BMI and race/ethnicity.