EVALUATION OF A NEW EMBRYO-GRADING SYSTEM TO PREDICT PREGNANCY RATES FOLLOWING IN-VITRO FERTILIZATION

This study examines two descriptive parameters of embryo morphology to determine if either parameter correlates with subsequent pregnancy ra tes (PRs). The two parameters were the evenness (similarity in size) o f the blastomeres and the degree of cellular fragmentation. A total of 242 embryo transfers in which 4 embryos were transferred were include d. Sixty-nine (28.5%) clinical and 62 (25.6%) viable pregnancies resul ted. In all cases 4 embryos were transferred, but the number of embryo s with even round blastomeres (grade 1) varied from 0 to 4. Statistica lly, there was no correlation between PR and number of grade 1 embryos transferred. When 4 grade 1 embryos were transferred, the PR was 33.3 versus 28.1% when no grade 1 embryos were transferred. There was, how ever, a statistical difference in the implantation rate; a higher freq uency of multiple gestations occurred when 3 or 4 of the embryos trans ferred were graded 1:12.7 as compared with 6.7% when less than or equa l to 2 embryos were grade 1. The significance of the degree of cellula r fragmentation in the embryos was also assessed. There was no statist ical difference in the PR according to the number (0-4) of embryos tra nsferred that did not have fragments (grade A). When 4 grade A embryos were transferred, the PR was 18.2 versus 26.1% when there were no gra de A embryos. Neither implantation nor multiple-birth rates correlated with fragmentation.