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.

Key Words: Frozen-thawed embryo transfer, FSH, age, clinical pregnancy, live birth