Serum anti-Müllerian hormone levels are negatively related to Follicular Output RaTe (FORT) in normo-cycling women undergoing controlled ovarian hyperstimulation.

BACKGROUND: Since in rodents anti-Müllerian hormone (AMH) has been shown to inhibit antral follicle responsiveness to FSH, we aimed at verifying whether a relationship exists between serum AMH levels and antral follicle responsiveness to exogenous FSH in normo-cycling women.
METHODS: Serum AMH, estradiol (E(2)) and FSH levels were prospectively measured on cycle day 3 in patients undergoing controlled ovarian hyperstimulation (COH) with a time-release GnRH agonist and standardized FSH doses. In 162 patients, follicles were counted after pituitary suppression and before FSH administration (baseline; small antral follicles; 3-8 mm), and on the day of hCG (dhCG; pre-ovulatory follicles; 16-22 mm). Antral follicle responsiveness to FSH was estimated by the Follicular Output RaTe (FORT), determined by the ratio pre-ovulatory follicle count on dhCG × 100/small antral follicle count at baseline.
RESULTS: Serum AMH levels were positively correlated with the number of small antral follicles at baseline (r = 0.59; P < 0.0001) and pre-ovulatory follicles on dhCG (r = 0.17; P < 0.04). Overall, FORT was 47.5 ± 1.4% and failed to be influenced by the woman's age, BMI or basal E(2) and FSH level. Conversely, multiple regression analysis showed that FORT was negatively correlated with AMH levels (r = -0.30; P < 0.001), irrespective of duration of COH and total FSH dose.
CONCLUSIONS: The percentage of follicles that effectively respond to FSH by reaching pre-ovulatory maturation is negatively and independently related to serum AMH levels. Although the mechanisms underlying this finding remain unclear, it is in keeping with the hypothesis that AMH inhibits follicle sensitivity to FSH.