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 normogonadotropic women followed a fixed 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 on 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.