Determinants of early follicular phase gonadotrophin and estradiol concentrations in women of late reproductive age.

ABSTRACT

BACKGROUND: FSH and estradiol measured during the menstrual (basal) phase of cycles predict the success of infertility treatment; but the role of these hormones as markers for ovarian reserve in normal populations needs further study. METHODS AND RESULTS: From a cohort study of depressed and non-depressed women, a subset of 406 non-depressed women between the ages of 36 and 45 years with spontaneous periods were selected and their concentrations and determinants of basal hormones measured at study entry, 6 and 12 months later were described. FSH and LH increased significantly over the 12 months of observation (P estradiol in some women monitored over the three cycles. Concentrations often varied between a pattern of low FSH, high estradiol in one cycle and high FSH, low estradiol in another. In multivariate models focusing on the maximum observed hormone concentration, significant predictors included increasing age (P < 0.0001), smoking (P = 0.04), and shorter cycle length (P < 0.0001) during adolescence (P < 0.0001) associated with higher FSH; increasing age (P < 0.0266) and lower body mass index (P < 0.0289) associated with higher LH; and a greater number of estimated ovulatory cycles associated with higher estradiol (P < 0.0425).

CONCLUSIONS:

Early reproductive landmarks, smoking, body weight, and factors that determine number of ovulatory cycles impact on ovarian/pituitary physiology in late reproductive life.