Gender does not impact the developmental rate of in vitro fertilization-derived human embryos as confirmed by day 3 blastomere biopsy and preimplantation genetic diagnosis (PGD)

Abstract

Background: An increase in male offspring has been described in different mammalian species following the transfer (ET) of faster-cleaving embryos. An association between ET of more advanced embryos and a higher male to female offspring sex ratio has also been observed by some in vitro fertilization (IVF) programs especially when human embryos are transferred at the blastocyst stage. Objective: To determine if gender has any impact on the developmental rate of IVF-derived human embryos prior to implantation. Materials and Methods: An IRB-approved retrospective review of 500 embryos undergoing PGD (67 IVF cycles) from 2002–2003. Oocyte retrieval and ICSI were performed according to standard protocols. Embryos were biopsied on day 3 of development and gender was determined by fluorescence in situ hybridization (FISH) with probes specific for the X and Y chromosomes. Embryos were classified by FISH as having a normal [female (XX) or male (XY)] or abnormal complement of sex chromosomes. After biopsy, embryos at 6 cells or greater were placed into extended culture and morphologically assessed for ET at the blastocyst stage of development. Embryos were also assessed at 24 hours postinsemination for cleavage status (cleavage, pronuclei/syngamy [PN-S], or pronuclei/non-syngamy [PN-NS]), and on day 2 and day 3 for blastomere number. Statistical analysis was performed using Chi-square analysis. Results: FISH analysis revealed 399 normal embryos (186 male:213 female) and 101 abnormal embryos (35 male: 54 female:12 nullisomic). Cleavage stage development rates between male or female embryos (normal [Tables I-III], abnormal or total) were equivalent. Four hundred and forty-one (441) cleavage stage embryos were available for extended culture of which 357 were normal (167 male:190 female) and 84 were abnormal (32 male:44 female:8 nullisomic). In extended culture, no difference was identified in developmental rates between normal male or female embryos (Table IV) but embryos abnormal for male or female sex chromosomes exhibited a slower developmental rate (p<0.001). Conclusions: Gender does not impact the rate of development through early embryogenesis. Consistent with reported literature, the decrease in development of embryos with abnormal sex chromosome complements in extended culture is most likely related to aneuploidy and not gender. ART- Preimplantation Genetic Diagnosis