Early follicle development alters the relationship between antral follicle counts and inhibin B and follicle-stimulating hormone levels on cycle day 3

Abstract

To verify whether, during the luteal-follicular transition, increased inhibin B production by abnormally large follicles modifies the expected relationship between the number of follicles and peripheral inhibin B and FSH levels. Prospective study. Teaching hospital, France. A total of 192 normo-ovulatory women. Serum inhibin B and FSH levels and numbers and sizes of antral follicles (3-12 mm) were measured on cycle day 3. The strength of hormonal-follicular correlations was assessed in two groups formed according to the presence (large follicle group; n = 73) or absence (small follicle group; n = 119) of one follicle measuring >7 mm. Serum inhibin B and FSH levels were correlated with antral follicle counts (r = 0.32 and r = -0.44, respectively). These relationships were significantly weaker in the large follicle group (r = 0.24 and r = -0.28, respectively) than in the small follicle group (r = 0.51 and r = -0.55, respectively). Antral follicle size influences serum inhibin B and FSH levels and alters their expected relationship with the number of antral follicles on day 3. These results contribute to clarifying the controversial role of serum inhibin B and FSH levels in the prediction of ovarian follicular status.