The pre-ovulatory surges of GnRH and LH are activated by increased concentrations of circulating estradiol, but ovulation is blocked when progesterone concentrations are elevated, due to a central inhibition of the GnRH surge. Although traditionally GnRH has been traditionally considered the drug of choice to control endogenous LH in controlled ovarian stimulation (COS) cycles, recently, micronized progesterone has been shown to be an effective oral alternative for preventing premature LH surges during COS in women undergoing IVF/ICSI treatments, with excellent results, whereas their safety during pregnancy is well-established. This novel protocol, has several advantages (good tolerance, user convenience, and cost reduction), that are very attractive when it comes to establishing a convenient user regimen in combination with a ''freeze all'' strategy. However, the comparative efficacy of this novel protocol with the more universal use of GnRH-antagonist protocol for the treatment of IVF patients in terms of embryo ploidy has never been evaluated up to date. The current study aims, for the first time, to examine whether the number of euploid embryos following ovarian stimulation with micronized progesterone is equivalent as compared with the number of embryos after ovarian stimulation with the use of a GnRH antagonist in patients undergoing ovarian stimulation for IVF/ICSI.
If efficacy would prove to be similar, with no impact on the chromosomal constitution of embryos, there will be obvious advantages for the preferential use of micronized progesterone over the antagonist protocol: oral administration is preferred over subcutaneous injection, and total cost of medication would be lower. This would be particularly interesting for the future in all "freeze all" protocols such as women undergoing ovarian stimulation for fertility preservation, preimplantation genetic screening and oocyte donation programs.
