Role of embryo morphology in Intracytoplasmic Sperm Injection cycles for prediction of pregnancy

Background:Multiple factors have been suggested for prediction of pregnancy in Intracytoplasmic sperm injection (ICSI) cycles such as the number of injected oocytes, fertilization rate, embryo morphology and quality of transferred embryos. Predictive value of these factors is important in ICSI outcome.
Objectives: To evaluate the role of embryo morphology for prediction of pregnancy in ICSI cycles.
Materials and Methods: This retrospective study was done on 97 patients who were treated by ICSI in Fatemeh Zahra Fertility and Infertility Centre from April 2004 to March 2005. Number of retrieved oocytes, number of injected oocytes, fertilization rate, zygote morphology, rate of cytoplasmic fragmentation, number of four cell transferred embryos, and quality of embryo transfer, as predictors of pregnancy in ICSI cycles were evaluated. The results analysed by T-test, Mann-Whitney U test and Fisher's exact test. Logistic regression was used to estimate the significance of variables in the prediction of pregnancy probability.
Results: Out of 97 patients, 42 cases of pregnancy were detected (Pregnancy rate: 43.3%). The number of four cell transferred embryos was 112 (53.84%) in pregnant group. Pregnancy occurred in 33 (58.9%) patients with at least one good quality zygote. The mean number of four cell transferred embryos and the quality of zygotes had significant difference between pregnant and not pregnant groups (p=0.006 and p=0.000 respectively). In logistic regression analysis, the number of four-cell transferred embryos (p=0.007) and the quality of zygotes (p=0.003) were significant predictors of the pregnancy outcome.
Conclusions: Our results suggest that thenumber of four-cell transferred embryos with ≤ 15% cytoplasmic fragmentation and zygotes with centralized, apposed and polarized pronuclei in women <38 years old are significant predictors for pregnancy in ICSI cycles.

Keywords
Intracytoplasmic sperm injection, Pregnancy prediction,Zygote morphology, Four-cell transferred embryos