Preimplantation testing for chromosome aneuploidy

•  Around 50% of cleavage stage human embryos obtained by in vitro fertilisation (IVF) have an abnormal number of chromosomes. •  Aneuploidy testing has been introduced at some IVF centres with the aim of identifying and removing abnormal embryos and increasing pregnancy success rates. •  Randomised controlled trials have indicated that pregnancy and live birth rates are lower for women undergoing aneuploidy testing.Learning objectives:•  To understand the nature and frequency of chromosome abnormalities in cleavage stage human embryos. •  To understand the rationale underlying aneuploidy testing. •  To understand the results of research on aneuploidy testing.Ethical issues:•  Should aneuploidy testing be offered, when randomised trials indicate either that it has no effect or that it results in fewer ongoing pregnancies and live births?Please cite this article as: Ogilvie CM. Preimplantation testing for chromosome aneuploidy. The Obstetrician & Gynaecologist 2008;10:88–92.