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

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

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

Healthy women aged 21-35 and 45-55 yr submitted three blood samples a week over a single menstrual cycle. They were classified as mid-reproductive age (n = 21), late-reproductive age (n = 16), early menopause transition (n = 16), and late menopause transition (n = 23).

There were nine, one, zero, and two anovulatory cycles identified in the late menopause transition, early menopause transition, late-reproductive age, and mid-reproductive age groups, respectively. Ovulatory cycle FSH, LH, and estradiol levels increased with progression of STRAW stage (P = 0.001, P < 0.01, and P < 0.05, respectively), and mean luteal phase serum progesterone decreased (P < 0.01). Early cycle (ovulatory and anovulatory) inhibin B 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 decreased markedly (10- to 15-fold) and progressively across the STRAW stages (P < 0.01 and P < 0.001, respectively).

Progression through the STRAW stages is associated with elevations in serum FSH, LH, and estradiol and decreases in luteal phase progesterone. The marked fall in inhibin B and particularly anti-Mullerian hormone 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.