Endocrine Features of Menstrual Cycles in Middle and Late Reproductive Age and the Menopausal Transition Classified According to the Staging of Reproductive Aging Workshop (STRAW) Staging System

Abstract

To date, the endocrine changes accompanying female reproductive aging have been quite variable and unpredictable. The first standardized guidelines were drawn up at the Stages of Reproductive Aging Workshop (STRAW) in 2001. The present investigators attempted to describe comprehensively the endocrinological features associated with STRAW stages. Healthy women 21–35 and 45–55 years of age submitted 3 blood samples each week during a single menstrual cycle. The 21 younger women served as mid-reproductive age (MRA) controls with regular menstrual cycles. The 56 older women were classified at STRAW stage 3, late reproductive age (LRA) with regular cycles (n = 16); STRAW stage 2, early menopause transition (EMT) with cycles of varying length (n = 17); and STRAW stage 1, late menopause transition (LMT) with at least 1 intermenstrual interval of 60 days or longer (n = 23). The numbers of anovulatory cycles were 9, 1, 0, and 2, respectively, in the LMT, EMT, LRA, and MRA groups. Ovulatory-cycle levels of follicle-stimulating hormone (FSH), luteinizing hormone, and estradiol all increased with the progression of STRAW stage. Mean luteal-phase levels of serum progesterone declined. Early-cycle (ovulatory and anovulatory) levels of inhibin B declined steadily across STRAW stages, and it was largely undetectable during elongated ovulatory and anovulatory cycles in the menopausal transition. Levels of anti-Müllerian hormone decreased markedly by as much as 15-fold across the STRAW stages. These findings, although not conclusive, suggest that both inhibin B and anti-Müllerian hormone may be preferable to FSH for predicting STRAW stage with respect to the onset and progression of the menopausal transition.