Relationship between even early cleavage and day 2 embryo score and assessment of their predictive value for pregnancy.

The aim of this study was, firstly, to define the different patterns of early cleavage (EC) observed at 26 h after either IVF or intracytoplasmic sperm injection (ICSI) and, secondly, to assess the predictive value of one of these patterns, even EC (EEC), on pregnancy rate in combination with day 2 embryo score. In the first part of the study, the relationship between three different EC patterns (EEC, uneven EC and EC with fragmentation of the day 2 embryo) and embryo morphology was determined. EEC was shown to be strongly associated with good embryo morphology. In the second part of the study, it was shown that EEC used in combination with embryo score improved selection of embryos for transfer. The presence of EEC significantly (P < 0.001) enhanced mean implantation rate in all transfer categories involving identically scored embryos, in both compulsory single embryo transfers and elective single embryo transfers. Multivariate analysis demonstrated that EEC and embryo score had strong complementary predictive value for pregnancy. Based on these findings, it was concluded that even though they are associated, EEC and embryo score could be combined to increase pregnancy rate, especially in elective single embryo transfer programmes.