Factors related to successful ovulation induction in patients with WHO group II anovulatory infertility

To identify baseline characteristics related to successful ovulation induction, data were analysed from oligo- or anovulatory patients undergoing their first cycle of human recombinant FSH (r-hFSH; follitropin alfa) in a chronic low-dose (75 IU starting dose), step-up protocol in two clinical trials (n = 446). Patients were grouped according to response: group A, ovulated within 14 days (75 IU follitropin alfa); group B, ovulated after 14 days (>75 IU follitropin alfa); group C, not administered human chorionic gonadotrophin (HCG) because of poor response; group D, cycle cancelled due to over-response (HCG not administered); group E, spontaneous ovulation prior to obtaining criteria for administration of HCG. Mean body mass index (BMI) of group A (25.0 kg/m2) was significantly lower than groups B (27.1 kg/m2, P < 0.001) or C (28.2 kg/m2, P < 0.0001), but similar to group D (24.3 kg/m2). Mean antral follicle count (AFC) of group A was also significantly lower than group C (18.3 versus 22.7; P = 0.018), but not significantly different from groups B (21.5) or D (19.5); group E had the highest mean AFC (35.7). Comparatively low BMI, low AFC and higher (although still within the normal range) FSH concentration at baseline were associated with successful ovulation induction in infertile women undergoing a chronic low-dose, step-up stimulation protocol.