Early cleavage: an additional predictor of high implantation rate following elective single embryo transfer.

The value of early cleavage (EC) assessment is still being debated. The aim of this prospective study was to examine the predictive value of EC assessment performed exactly 26 h after insemination by IVF or intracytoplasmic sperm injection (ICSI) in a programme of elective single embryo transfer (SET) performed at day 2. If day 2 scoring demonstrated several embryos with high implantation potential, an EC embryo was transferred preferentially. EC was assessed only during normal laboratory hours so that there were two groups: EC assessed, and EC not assessed, the latter being the control. A total of 277 elective SET were performed in women under 37 years undergoing their first IVF or ICSI cycle (mean age 30.5 years, range 21-37). The overall clinical and ongoing pregnancy rates were 40.1% (111/277) and 32.9% (91/277) respectively. Significantly higher overall clinical and ongoing pregnancy rates were obtained after transfer of an EC embryo than a non-EC embryo: 49.4 versus 33.3% (P < 0.05) and 42.4 versus 25.9% (P < 0.02) respectively. However there was no significant difference between the EC assessed and control groups: 40.4 versus 39.3% and 33.2 versus 32.1 respectively. These findings confirm the value of EC assessment for selection of embryos with high implantation potential.