Gene expression and cleavage arrest in the human embryo.

In vitro fertilisation and embryo transfer (IVF-ET) is now an accepted part of clinical practice for the treatment of infertility offering live birth rates in the region of 24% per cycle when three embryos are returned to the uterus However analysis of success in terms of the number of established conceptions per embryo returned reveals that only 10.9% of embryos transferred implant. Achieving improved success for IVP-ET, especially following the replacement of a single embryo in order to reduce the risk of multiple pregnancy is undoubtedly dependent on an improved understanding of the mechanisms that lead to embryonic failure.