Published reports have indicated that rates of preimplantation embryo aneuploidy in a control donor population may vary between IVF centres. This suggests that location-specific conditions, in the clinic, IVF or genetics laboratory, may be influencing the chromosome dynamics or diagnosis. More recent reports suggest that rates of embryo mosaicism, representing mitotic errors, may vary between IVF centres. This would suggest perhaps a laboratory-controlled variable is influencing mitotic cell division during preimplantation embryo development. Various IVF laboratory-controlled factors may be impacting chromosome separation and segregation. Variables including type of culture media, pH, temperature, osmolality and oxygen concentration could all be possible factors influencing embryo aneuploidy. Furthermore, laboratory techniques, method of insemination, laser use or handling of biopsied cells may also influence genetic results. These IVF laboratory variables will be reviewed and literature suggesting a possible link to mitotic aneuploidy/mosaicism discussed.