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, oil 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 ill 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 = 7 1; 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. (Fertil Steril (R) 2009;92:1269-75. (C) 2009 by American Society for Reproductive Medicine.)