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.
Level 4 - case-series / case-control
Cross-sectional observational study characterizing hormonal profiles across four STRAW staging groups over a single cycle.
PubMed 17550960 · doi:10.1210/jc.2007-0066
What was done
Healthy women aged 21–35 and 45–55 submitted blood samples three times per week over a single menstrual cycle. Participants were categorized by STRAW criteria into mid-reproductive age (n = 21), late-reproductive age (n = 16), early menopause transition (n = 16), and late menopause transition (n = 23; total n = 76). Endocrine markers—including FSH, LH, estradiol, luteal progesterone, inhibin B, and anti-Müllerian hormone (AMH)—were measured across ovulatory and anovulatory cycles.
What was found
Anovulatory cycles occurred in 9 women in late menopause transition, 1 in early menopause transition, 0 in late-reproductive age, and 2 in mid-reproductive age. Across ovulatory cycles, advancing STRAW stage was associated with significant increases in FSH (P = 0.001), LH (P < 0.01), and estradiol (P < 0.05), alongside decreased mean luteal-phase progesterone (P < 0.01). Early-cycle inhibin B decreased progressively across STRAW stages (P < 0.01) and was largely undetectable in elongated ovulatory and anovulatory transition cycles. AMH decreased progressively and markedly (10- to 15-fold) across STRAW stages (P < 0.01 and P < 0.001).
Why it matters
The findings show how specific endocrine shifts—notably marked declines in AMH and inhibin B alongside rising gonadotropins—align with clinical STRAW staging criteria for reproductive aging.
Limits
The sample size is modest (76 participants total across four subgroups) and restricted to a single cycle rather than longitudinal follow-up. Absolute hormone concentrations, variability estimates, and confidence intervals are not provided in the abstract.
Cited by
- supports Early perimenopause often features a shortening of the menstrual cycle, whereas late perimenopause is characterized by lengthened cycles and frequent anovulatory cycles.