Selection of good embryos for transfer depends on embryo cohort size: implications for the `mild ovarian stimulation' debate

Abstract

Embryo quality evaluated by the embryo morphology is a critical parameter in human in-vitro fertilization (IVF) and embryo transfer. It determines which and how many embryos will be replaced, as pregnancy rates are directly related to number and quality of transferred embryos. This retrospective analysis included 1301 IVF and embryo transfer cycles to identify which factors influenced embryo quality. Embryo quality did not correlate with maternal age, causes of infertility, ovarian stimulation parameters or embryo cohort size. However, the mean score of transferred embryos was significantly higher for patients with more than five embryos compared to fewer than five embryos (P < 0.001), irrespective of maternal age. Patients tended to produce a similar embryo quality from cycle to cycle, r = 0.33 (P < 0.001) for the embryo cohort and r= 0.47 (P < 0.001) for the transferred embryos. Poor embryo morphology probably reflects oocytes with compromised development competence and could be an independent factor of infertility. Furthermore, a large embryo cohort was the main factor increasing the chances of at least one good embryo in the cohort.

In-vitro maturation of human oocytes: before or after vitrification?

“…Oocyte retrieval was performed through vaginal puncture under ultrasound guidance 36 h later. Oocyte collection and laboratory procedures are described elsewhere [17]. After the oocyte collection, the oocyte-cumulus complexes were denuded using finely drawn pipettes (170-130 μm) following 1 min of exposure to 80 IU/ml hyaluronidase solution (Sigma Aldrich SrL, UK.).…”

Oral contraceptive pill pretreatment in ovarian stimulation with GnRH antagonists for in vitro fertilization: A comparative study

“…This phenomenon potentially reduces the number of viable oocytes and embryos and the probability of conception. Selection of good embryos for transfer depends on embryo cohort size: implications for the `mild ovarian stimulation' debate [10]. The number of embryos available for transfer predicts successful pregnancy outcome in women over 39 years with normal ovarian hormonal reserve testing [11].…”

“…54, No. 10,2011 pills (OCP) pretreatment has been reported to induce higher numbers of oocytes retrieved compared to no pretreatment group in GnRH antagonist cycles [8]. However, OCP pretreated GnRH antagonist cycles presented longer duration and needed more larger amount of gonadotropin for stimulation than no pretreatment cycles [8,9].…”

Does the Number of Retrieved Oocytes Influence Pregnancy Rate After Day 3 and Day 5 Embryo Transfer?

“…Furthermore, endometrial quality can also be hampered in high-dose stimulating protocols (Gougeon, 1996;Pal et al, 2008). On the other hand, higher number of oocytes simply allows for better selection of quality embryos from a larger cohort of available embryos (Devreker, 1999;Pal et al, 2008).…”