The correlation between basal serum follicle-stimulating hormone levels before embryo cryopreservation and the clinical outcome of frozen embryo transfers.

OBJECTIVE: To evaluate the correlation between basal serum FSH level before the fresh IVF/intracytoplasmic sperm injection (ICSI) cycle and the clinical outcome of the subsequent frozen embryo replacement cycles.

DESIGN: Retrospective observational study.

SETTING: University tertiary referral center, London, United Kingdom.

PATIENT(S): Five hundred four consecutive frozen embryo transfer (FET) cycles where serum FSH levels were obtained, on days 1-4 of the cycle before the fresh IVF +/- ICSI cycles.

INTERVENTION(S): Frozen-thawed embryo transfer.

MAIN OUTCOME MEASURE(S): Clinical pregnancy (CP) and live birth (LB).

RESULT(S): Basal serum FSH in 127 women (25.2%) who had a CP was significantly lower compared with that in women who did not have a CP. Multivariate regression analysis showed significant correlation between basal serum FSH levels and clinical pregnancy and a low significance to LB, but there was no statistical significant differences between women who had a CP and those who did not with regard to age, treatment protocol (natural or hormone treatment cycle), or the freeze-thaw interval. The LB rate was higher in natural cycles (n = 71; 21.2%) than in hormone treatment cycles (n = 28; 16.7%). Conceiving in the fresh cycle had a positive influence on the FET outcome.

CONCLUSION(S): Basal serum FSH level before fresh IVF/ICSI cycle is inversely correlated to a CP outcome in FET cycles. A trend was present between FSH levels and LB, but this failed to reach statistical significance.