Does transfer of a `top quality zygote or embryo increase chances of success after IVF?
The data obtained from 154 cycles of IVF where a total of 551 embryos was replaced on day 2 (40 41 h) or day 3 (64 65 h) after scoring zygote or embryo quality on each day of culture were analysed retrospectively. In previous IVF cycles (where zygote morphology was not considered), a pregnancy rate of 37.4% and implantation rate of 16.5% were achieved (among 182 patients treated between January 1998 and January 1999, with mean maternal age 33.2 ± 8.4 years and mean of 3.5 ± 1.3 embryos transferred). These values were used as baseline to permit accurate evaluation of the scoring system presented in the present data. When zygote scores were considered alone, minimal correlation was observed between quality and predictability. Embryos derived from group 1 zygotes achieved 25/59 pregnancies (42.4%), with an implantation rate of 13.2% (mean 3.4 ± 1.1 embryos transferred; Figure 3, Table II). However, embryos derived from group 2 zygotes resulted in 40/89 pregnancies (44.9%) with an implanta
