singapoh, hazel,
both my embbies are grade 4 on fresh cycle, but i still failed. i ask dr loh what has cause my failure, cos i kept blaming on my womb that couldnt implant both of them. But he told me grade is only determined by its appearance. if it looks nice with correct cells and no fragmentations, then it has the best grade. but the quality of the embryos is determined by its genetic chromosome. u wont know if its good quality until further test is done on its chromosome. if ur quality is good, it will continue to grow, to divide into more cells and eventually to hatch out. Even if its excellent grade, having grade 5 at day2, it may die off after day 3 or 4, you will not know.
dr loh told me there is a case study in US. a woman tried ivf a few times, but always BFN even though her grades were good. ultimately they did a research on her embryos. they remove every single cell in the embryo to test and realise there is some chromosome problems that the embryos couldnt survive.