Characterization and prediction of IVF cycles generating "slow-cleaving" embryos.

PURPOSE: To characterize and predict cycles generating open quote slow-cleaving closed quote embryos in in vitro fertilization, 86 cycles were retrospectively divided into two groups (open quote slow, closed quote n=41, and open quote fast, closed quote n=45) according to whether the number of blastomeres per embryo on day 3 was < or = or > than the mean of the distribution, respectively.
RESULTS: Cycles generating open quote slow-cleaving closed quote embryos were treated with luteinizing hormone-releasing hormone agonist before ovarian stimulation for a shorter period (12.1 +/- 0.5 versus 15.6 +/- 1.1 days; P < or = 0.01) and had higher immaturity grade of oocyte-corona-cumulus complexes which resulted in embryos (1.6 +/- 0.1 vs 1.3 +/- 0.1; P < or = 0.05) when compared to cycles producing "fast-cleaving" embryos. Both variables entered in a logistic regression model applied in order to predict the probability of a cycle generating "slow-cleaving" embryos (goodness-of-fit chi-square = 180.0, degrees of freedom (df) = 80, P = 0.4786). This model predicted correctly 86.7% (13 of 15) of cycles generating "slow-cleaving" embryos and 83.3% (10 of 12) of cycles producing "fast-cleaving" embryos when the estimated probability of a cycle producing "slow-cleaving embryos" was > or = 0.7 or < or = 0.3, respectively.
CONCLUSION: Shorter treatment with hormone-releasing hormone agonist before ovarian stimulation and higher immaturity grade of oocyte- corona-cumulus complexes which result in embryos are predictive characteristics of in vitro fertilization cycles generating "slow-cleaving" embryos.