Follicular fluid insulin-like growth factor-I and insulin-like growth factor-II concentrations vary as a function of day 3 serum follicle stimulating hormone.

We determined follicular fluid concentrations of insulin-like growth factor (IGF)-I, IGF-II and inhibin as a function of day 3 serum follicle stimulating hormone (FSH) in 16 women undergoing follicular fluid aspiration in preparation for in-vitro fertilization and embryo transfer. Follicular fluid concentrations of IGF-I and IGF-II were significantly less in the 'low' FSH group as compared to the 'high' FSH group. The mean IGF-I concentration was 67.6 ng/ml [confidence intervals (CI) 51.6-92.5] in the 'low' FSH group compared to 87.1 ng/ml (CI 72.8-104.2; P < 0.025) in the 'high' FSH group. Mean IGF-II concentrations were 354.8 ng/ml (CI 297.8-422.9) in the 'low' FSH group compared to 489.8 ng/ml (CI 384.6-624.5; P < 0.05) in the 'high' FSH group. Follicular fluid inhibin concentrations did not differ between groups. These differences in follicular fluid IGF as a function of day 3 FSH may raise questions regarding the role growth factors play in the physiological processes of the ageing follicle.