Detailed definition
Ovarian reserve is a clinical concept describing the remaining pool of follicles available for ovulation and the quality of those follicles. Women are born with approximately 1–2 million primordial follicles; by puberty, around 300,000–400,000 remain; by age 37 the cohort has fallen to roughly 25,000; by menopause, only a few hundred. Loss occurs through atresia (most follicles) and ovulation (a tiny fraction). Clinical markers of reserve include serum AMH (the most-used single marker, stable across the cycle), antral follicle count on transvaginal ultrasound (counting small follicles 2–10 mm), and FSH on cycle day 3 (less reliable in perimenopause due to fluctuation). Diminished ovarian reserve correlates with reduced fertility potential and shorter time-to-menopause.
Why it matters in menopause
For women considering fertility planning in their late 30s and 40s, ovarian reserve testing helps shape decisions. For women asking "how soon will I be in menopause," reserve testing gives only a rough trajectory — there is no precise predictor of FMP date.
Related terms
Sources
External references: Wikipedia.