Reduced in vitro fertilization of human oocytes correlates with raised circulating FSH levels during ovarian stimulation in normogonadotropic women downregulated with GnRH-analogues

Purpose: The possible effects of circulating FSH levels as used during IVF treatment on oocyte maturation and subsequent preembryo development were evaluated. Methods: Serum levels of FSH and LH on days 1 and 8 of ovarian stimulation and on the day of oocyte retrieval (OR) were correlated with subsequent preembryo development in vitro. After pituitary downregulation, 244 normogonado-tropic women followed a Fred protocol for the first 7 days of stimulation. Results: The average FSH concentration on day 8 of stimulation was 11.5 IU/L and exceeded the expected midcycle surge of FSH by more than 25%. In contrast, levels of LH were below an average of 2 IU/L throughout the stimulation period. The concentration of FSH on day 8 and oil the day of OR Showed a significant inverse correlation with cleavage rate, whereas levels of LH, age, and body mass index showed no such correlation. Conclusions: Supraphysiologic levels of FSH seems to affect oocyte maturation negatively. Premature resumption of meiosis, leading to retrieval of postmature oocytes with a reduced developmental potential, is suggested as the underlying mechanism.