The predictive value of pronuclear morphology screening on embryo development and pregnancy outcome in ART cycles

Objective: To evaluate the predictive value of zygote pronuclear (PN) morphology on embryo development and pregnancy outcome in in-vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) cycles.Materials and Methods: PN morphology of embryos resulted from 35 IVF and 35 ICSI cycles were evaluated. The cause of infertility for IVF and ICSI patients were tubal and male factor of infertility, respectively. After PNassessment using Z-scoring, the zygotes were incubated individually in drops of culture media and evaluatedblindly. Embryo transfer (ET) took place either on day-2 or day-5.Results: Significant differences were noticed between Z1 and Z4 scoring embryos. The Z-scoring system was useful inpredicting day-2 and -5 embryo survival and development. There was a direct correlation with Z1 and grade Aembryo formation, also between Z2 and blastocyst development in both IVF and ICSI cycles. The pregnancy ratesin IVF and ICSI were 25.7% and 22.9%, respectively. Day-2 ET derived from Z1 and Z3 zygotes, and day-5 ETresulted from Z1 and Z2 zygotes were involved with high pregnancy rates.Conclusion: PN morphological assessment can predict further embryonic development and pregnancy outcome in ARTcycles. The Z-score could be of a helpful tool in the selection of embryos both in cellular and blastocyst stage for transfer to achieve high pregnancy rates.