What is the success rate of IVF pregnancies? This varies from 40 to 50 percent. This success rate depends on various factors, the important on e s being embryo quality Endometrial thickness and endometrial receptivity Grade 1 embryos w ith no or minimal fragmentation have better success rates. Blastocyst transfer has better success rates. Endometrial receptivity can be assessed by a test called ERA. Above this all being stress free also adds to a high success rate