While both COCPs and luteal estradiol suppress the luteal rise in FSH and synchronize follicles, they have not been compared against each other. COCPs, with progestin in addition to estrogen, may achieve better suppression of luteal FSH than estradiol and result in better synchronization of the follicles. COCPs, however, have been used to decrease ovarian responsiveness in patients with polycystic ovarian syndrome who are at increased risk of ovarian hyperstimulation syndrome.15 Therefore, COCPs may suppress ovarian responsiveness more than luteal estradiol, an unwanted effect in the poor responder population. One potential mechanism for greater ovarian suppression with COCPs may be the decrease in androstenedione, a marker shown to be positively correlated with total and mature oocyte number obtained during IVF, 16 subsequent to the COCP-induced increase in sex hormone binding globulin.