Cleavage Stage versus Blastocyst Stage Embryo Transfer: A Controlled Randomized Study

Background: Both cleavage-stage and blastocyst-stage embryo transfer policies have advantages and drawbacks. The number of embryos transferred, however, is a crucial parameter that needs to be considered before attempting any comparison. Advances in the dynamics of embryo culture allow us to culture embryos to the blastocyst stage on day 5). Prolonging the duration of culture to Day 5 allows chromosomally competent embryos to develop to the blastocyst stage and permits selection of embryos that has the potential for continued development under embryonic genomic control (1). In addition, selection of Day 5 embryos has the advantage of physiological synchronization with the uterine endometrial, thereby resulting in better pregnancy rates (2). Objective: The aim of this study is comparing intracytoplasmic sperm injection (ICSI) results: fertilization rate, Cleavage rate ( number& quality of embryos) and clinical pregnancy rate, to evaluate the efficacy of blastocyst transfer in comparison with cleavage stage transfer (4 cell stage & 8 cell stages).
Patients and Methods: 600 patients aged 25-40 years, who were scheduled for intracytoplasmic sperm injection cycle from Jan 2014 to Dec 2015, were recruited in the study. After assessment of fertilization, patients were divided randomly into three study groups, day 2, day 3 and day 5 embryo transfer groups having 200 patients each. Primary outcomes, clinical pregnancy rate and implantation rate were evaluated. Results: all the groups were similar for age, indication and number of embryos transferred. Clinical pregnancies after blastocyst transfer were significantly higher 51 % compared to cleavage stage embryo transfer 37% (day 2), 48.5 % (day 3). Conclusion: Blastocyst transfer having high implantation rate and clinical pregnancy rate leads to reduction in multiple pregnancies.