What does anti-Müllerian hormone tell you about ovarian function?

The measurement anti-Müllerian hormone (AMH) is leading to new insights into ovarian function. AMH is produced by small growing follicles, thus is distinct from ovulation and is a step closer to being able to assess the true ovarian reserve. AMH is measureable from birth to near the menopause, with a peak in the mid-20s. Changes in adolescence are likely to lead to new understanding of ovarian maturation at puberty. AMH is becoming a routine test in assisted conception, reflecting a decline in the primordial follicle pool during the later reproductive years, and also identifying women at risk of over-response. Thus, its relationship with the ovarian reserve changes from an inverse one in the first quarter century to a positive one thereafter as both decline in parallel. AMH does not vary significantly across the menstrual cycle, but it is not fully gonadotrophin-independent, showing delayed changes consistent with the site of production from smaller growing follicles. There is considerable interest, both professional and public, in its ability to predict remaining reproductive lifespan, which clinically may be of value in the assessment of ovarian reserve following damage, for example postchemotherapy or ovarian surgery. AMH is markedly increased in polycystic ovarian syndrome and may be of diagnostic value. The considerable promise of AMH measurement is ahead of the robustness of the data in allowing clinical interpretation in most contexts, but it is clear that it will in the future offer novel opportunities for the assessment of ovarian function in health as well as disease.