 It has recently been shown that the use of estradiol in the luteal phase of the preceding menstrual cycle may facilitate growth of follicles in a coordinated fashion 8, 11. Fanchin et al.11 prospectively studied 90 women who were undergoing IVF cycles using GnRH antagonists and randomly assigned them to receive either 4 mg of oral micronized estradiol from cycle day 20 until day 2 of the next cycle or to serve as controls and receive no estradiol treatment. They found that the group that received estradiol had significantly smaller follicles on day 8 of their cycle and had less of a discrepancy in follicle size.. The group that received estradiol also had more follicles that were 16 mm or greater, more mature oocytes, and more embryos than the control group. The clinical pregnancy rate was greater in the estradiol group although this finding was not statistically significant 34 vs. 25. 