Fanchin et al has demonstrated that luteal estradiol administration suppresses luteal FSH rise, reduces antral follicle size, and synchronizes the follicular cohort.3,4,5,6 Luteal estradiol and GnRH antagonist administration prior to controlled ovarian hyperstimulation for in vitro fertilization (IVF) have been shown to decrease cancellation rate, increase mean number of oocytes retrieved, and improve fertilization rates in poor responders (retrospective study using historic controls presented in abstract form).7 Estradiol has also been used in patients with hypergonadotrophic amenorrhea to suppress elevated endogenous LH and FSH prior to stimulation with exogenous gonadotropins with modest success in achieving ovulation and, in rare cases, pregnancy.8