Chromosomal Problems Affect Nearly all Human Embryos: Discovery May Explain Low Fertility Rates in Humans

For the first time, scientists have shown that chromosomal abnormalities are present in more than 90% of IVF embryos, even those produced by young, fertile couples. Ms Evelyne Vanneste, a PhD student in the Centre for Human Genetics and the University Fertility Center, Leuven University, Belgium, told the 25th annual conference of the European Society of Human Reproduction and Embryology today (Wednesday July 1), that the surprising finding meant that current techniques used in preimplantation genetic screening (PGS), where embryos are screened genetically in order to select the best embryo for transfer, do nothing to improve pregnancy and live birth rates. Indeed, it can lead to potentially viable embryos being discarded, she said.

You can read more about this study in this article:
http://www.sciencedaily.com/releases/2009/07/090701082919.htm