[Chromosome abnormalities of the fertilized human egg].

In vitro fertilization enabled the study of lethal (parthenogenesis) or sublethal (triploidy, monosomy and trisomy) chromosomal abnormalities in man. According to the literature, 23 to 71% of preimplantation embryos carry a chromosomal defect. Various factors, such as delayed fertilization, early embryo fragmentation or elevated maternal age (greater than 35 years) are related to an increase in the incidence of chromosomal aberrations. These data reinforce the debate on a preimplantation genetic diagnosis in order to select for transfer only viable and apparently normal embryos.