Does Recombinant FSH (rFSH, i.g. Gonal F®) as Compared to Human Menopausal Gonadotrophin (hMG) Affect Telomere Length of Cumulus Cells During Antral Follicle Growth and Impact Blastocyst Status?

Gonal-F® (follitropin alfa) is a recombinant human follicle-stimulating hormone (rFSH), without LH activity. Urine-derived, human-menopausal-gonadotropin contains LH and hCG. A highly purified hMG, HP-HMG, Menopur® has been compared with Gonal-F® in terms of ongoing pregnancy rate in the so called MEGASET trial ("Menopur in GnRH Antagonist Cycles with Single Embryo Transfer") and both showed to be effective in GnRH antagonist cycles with SET. Another non-inferiority study was initiated in high responders - MEGASET-HR-, comparing Menopur with Gonal-F. After fresh transfer, the ongoing pregnancy rate was similar between groups: 35.5% for Menopur versus 30.7% for Gonal-F, and non-inferiority was established. However, cumulative early pregnancy loss from fresh embryo transfer cycles (ET) and frozen embryo transfer cycles (FETs) in patients treated with HP-hMG was significantly lower as compared to rFSH (14.5% vs 25.5%). Telomere length (TL) has been long proposed as oocyte quality marker and, recently, has been correlated with pregnancy outcomes. During folliculogenesis, granulosa cells undergo successive cell divisions which can result in telomeric shortening. Telomerase is the enzyme complex that binds the chromosome ends (telomeres) and maintains telomere length and integrity. An association has been shown between telomere length in cumulus cells (CC), oocyte competence and embryo quality. Hence, with the present study, the investigators aim to explore whether the stimulation treatment type (hMG versus Gonal-F) affects the telomere length of oocytes cumulus cells reflecting on subsequent blastocyst development, to help understanding the underlying differences between both gonadotropins. To the investigators best knowledge, there are no studies evaluating TL in CC from the same patient exposed to two different stimulations. With the present, we intend to perform a randomized, open-label, cross-over study in a selected normo-responders patient population. Patients will be submitted to hormonal analysis, to analysis of telomere length of their oocyte cumulus cells and to analysis of quality markers of its respective embryos/blastocysts. This includes morphokinetics development, euploidy and mitochondria status evaluation of cultured blastocysts.