Developmental stage on day-5 and fragmentation rate on day-3 can influence the implantation potential of top-quality blastocysts in IVF cycles with single embryo transfer

Overall, in 203 cycles with SET, developmental characteristics of 93 implanted (group A) and 110 non-implanted (group B) advanced blastocysts of good quality were compared. The following developmental parameters were assessed in the two groups: normal fertilization, developmental stage on day 5, number of blastomeres on day 2 and on day 3, fragmentation rate on day 3, compaction on day 4 and cleavage pattern on day 2 and day 3.Expanded blastocysts compared to full blastocysts have higher implantation potential (56.5% vs. 29.3%, p < 0.05). In group B, a higher proportion of advanced blastocysts showed between 10% and 50% anucleated fragments on day 3 than in group A (23.6 vs 11.8, P = 0.03). Advanced blastocysts with >10–50% fragments on day 3 showed a significant lower implantation (29.7%) than those with ≤ 10%fragments (49.4%, P = 0.03). All the other parameters analysed were comparable for the two groups.Developmental stage on day 5 and fragmentation rate on day 3 were related to the implantation potential of advanced blastocysts and should also be taken into account in the selection of the best advanced blastocyst for transfer.The ultimate goal of assisted procreation is the birth of a singleton liveborn infant. Growing concerns have been raised regarding the risks of multiple pregnancies which consist of approximately 30% of the deliveries after assisted reproductive technology (ART) [1]. The only way to achieve this goal is to move towards single embryo transfer policy [2]. In order to prevent a significant decrease in pregnancy and delivery rates when only one embryo is transferred, the selection of that embryo for transfer should be optimal to ensure a high implantation rate.There is general agreement that a positive correlation exists between embryo quality and pregnancy rates [3]. Several studies, either on day 2 [4-9] have attempted to quantify the implantation potential of an embryo by means of scoring systems based on different embryological parameters s