CHARACTERIZATION AND PREDICTION OF IVF CYCLES GENERATING SLOW-CLEAVING EMBRYOS

Purpose: To characterize and predict cycles generating ''slow-cleaving '' embryos in in vitro fertilization, 86 cycles were retrospectively d ivided into two groups (''slow,'' n = 41, and ''fast,'' n = 45) accord ing to whether the number of blastomeres per embryo on day 3 was less than or equal to or > than the mean of the distribution, respectively. Results: Cycles generating ''slow-cleaving'' embryos were treated wit h luteinizing hormone-releasing hormone agonist before ovarian stimula tion for a shorter period (12.1 +/- 0.5 versus 15.6 +/- 1.1 days; P le ss than or equal to 0.01) and had higher immaturity grade of oocyte-co rona-cumulus complexes which resulted in embryos (1.6 +/- 0.1 vs 1.3 /- 0.1 P less than or equal to 0.05) when compared to cycles producing ''fast-cleaving'' embryos. Both variables entered in a logistic regre ssion model applied in order to predict the probability of a cycle gen erating ''slow-cleaving'' embryos (goodness-of-fit chi-square = 180.0, degrees of freedom (df) = 80, P = 0.4786). This model predicted corre ctly 86.7% (13 of 15) of cycles generating ''slow-cleaving'' embryos a nd 83.3% (10 of 12) of cycles producing ''fast-cleaving'' embryos when the estimated probability of a cycle producing ''slow-cleaving'' embr yos was greater than or equal to 0.7 or less than or equal to 0.3, res pectively. Conclusion: Shorter treatment with hormone-releasing hormon e agonist before ovarian stimulation and higher immaturity grade of oo cyte-corona-cumulus complexes which result in embryos are predictive c haracteristics of in vitro fertilization cycles generating ''slow-clea ving'' embryos.