Anti-FSH antibodies associate with poor outcome of ovarian stimulation in IVF.

FSH is required for spontaneous folliculogenesis and is widely used in ovarian stimulation in IVF. Previously, increased concentrations of antibodies against FSH (anti-FSH) have been demonstrated in infertile women. This study aimed to: (i) assess the possible association of anti-FSH with an adverse outcome of IVF with regard to clinical parameters characterizing the ovarian reserve; and (ii) compare serum and follicular fluid (FF) anti-FSH concentrations in relation to follicle size and endocrine markers. IVF patients (n = 182) subjected to gonadotrophin-releasing hormone-antagonist protocol were assessed for anti-FSH using enzyme-linked immunosorbent assay. Increased concentrations of serum anti-FSH immunoglobulin (Ig)G and IgA were associated with impaired ovarian stimulation outcome, with cut-off values <1.0 arbitrary units predicting poor ovarian response (<or=3 oocytes) (adjusted odds ratio for IgG = 6.95, P = 0.005 and IgA = 3.60, P = 0.039). FF anti-FSH IgG and IgA were positively associated with serum anti-FSH concentrations and FSH concentration in FF. Additionally, FF anti-FSH IgG increased with follicle growth (linear regression coefficient = 0.02, P = 0.022). Collectively, these data suggest that serum anti-FSH antibodies are associated with poor ovarian response to FSH stimulation in IVF, with anti-FSH IgA and IgG potentially exerting a local FSH antagonizing effect in maturing follicles.