[Statistical and prognostic correlation of serum levels of basal inhibin to response and follicular quality in assisted reproduction].

BACKGROUND: Inhibin B is a direct marker of ovarian reserve and one of the earliest markers of ovarian aging. It has been used in assisted reproduction programs as a serum marker that can identify an altered follicular reserve and predict a good or poor response to the stimulation with exogenous gonadotropins. OBJECTIVE: To correlate inhibin B levels with follicular response and quality of oocytes obtained through ovarian stimulation controlled in an in vitro fertilization cycle (IVFET), as well as relate it with variables such as: fertilization percentage and pregnancy rates. PATIENTS AND METHODS: In a prospective and transversal study we included 71 patients that entered the IVFET program (February-April 2005). We determined inhibin B levels at the third day of the cycle and evaluated the follicular response and the oocyte quality during the ovarian stimulation, as well as fertilization and pregnancy rates. Statistical analysis was made with Spearman's and ANOVA tests. RESULTS: We observed a positive correlation between inhibin levels and quantity of developed follicles (0.457), number of captured oocytes (0.390), and quantity of metaphase II oocytes (0.324). We observed better oocyte quality in women with inhibin levels > 251 pg/ mL, and we considered that the ones that had levels < 50 pg/mL had poor follicular response (19.71%). There was no correlation with fertilization and pregnancy rates. CONCLUSIONS: In the early follicular phase inhibin B has direct correlation with ovarian reserve. Its high levels are related to better follicular response and oocyte quality. This enzyme levels are not useful as a predictive factor of pregnancy in IVFET cycles.