Age-specific serum FSH concentrations and their correlation with the outcome of ovarian stimulation for IVF

The aim of this study was to investigate whether age-specific FSH concentration can be a predictor of the outcome of ovarian stimulation in women undergoing IVF, with various basal FSH (bFSH) concentrations but within the normal range, i.e. ≤9.5 IU/l. A total of 1373 women undergoing their first IVF cycle over a 5-year period were included in this retrospective cohort study. Patients were grouped according to age, and within each age range, patients were grouped into bFSH quartiles. The primary outcome measure was oocyte yield, and secondary outcome measures included number of normally fertilized oocytes (2PN), number of embryos transferred and frozen, as well as implantation, biochemical, and clinical pregnancy rates. In all study groups (25–29; 30–34 and 35–39 years), women with low bFSH concentrations had significantly more oocytes retrieved (P = 0.003; P < 0.0001 and P = 0.0001 respectively), and more normally fertilized 2PN embryos (P = 0.03; P < 0.0001 and P = 0.001 respectively) than those of the same age with ‘high’ normal bFSH concentrations. Although there was no significant difference in the secondary outcome measures, these were generally more favourable in patients with ‘low’ age-specific bFSH concentrations. The findings of this study suggest that age-specific FSH testing can serve as a good predictor of the oocyte yield in women with normal bFSH concentrations undergoing IVF.