Context: Female reproductive aging based on changes in menstrual cycle length and frequency, progresses through a number of stages as defined by the STRAW (Stages of Reproductive Aging Workshop) staging criteria.

Objective: This paper provides a comprehensive description of the endocrine features associated with the STRAW stages.

Design: Healthy women aged 21-35 and 45-55 submitted three blood samples a week for over a single menstrual cycle. They were classified as mid-reproductive age (MRA; N=21), late reproductive age (LRA; N=16), early menopause transition (EMT; N=16) and late menopause transition (LMT; N=23).

Results: There were 9, 1, 0 and 2 anovulatory cycles identified in the LMT, EMT, LRA and MRA groups respectively. Ovulatory cycle FSH, LH and estradiol (E₂) levels increased with progression of STRAW stage (P = 0.001; P < 0.01; P < 0.05 respectively), and mean luteal phase serum progesterone decreased (P < 0.01). Early cycle (ovulatory and anovulatory) inhibin B (INHB) decreased steadily across the STRAW stages (P < 0.01) and was largely undetectable during elongated ovulatory and anovulatory cycles in the menopause transition. Anti-Mullerian Hormone (AMH) decreased markedly (10-15 fold) and progressively across the STRAW stages (P < 0.01; P < 0.001 respectively).

Conclusions: Progression through the STRAW Stages is associated with elevations in serum FSH, LH, E₂ and decreases in luteal phase P. The marked fall in INHB and particularly AMH indicate that they may be useful in predicting STRAW Stage but future analyses of early cycle measurements on larger cohorts are needed to draw predictive conclusions.