At Monash IVF we prefer to transfer embryos five days after egg retrieval, when the embryo is at the blastocyst stage. Not all embryos have the ability to reach the blastocyst stage which is usually because there are inherent issues within the embryo, however if the embryo can become a blastocyst by day 5 or 6 it is more likely to result in a pregnancy.
Recent research has shown that embryos that can reach the blastocyst stage of development are more likely to be chromosomally balanced compared to 2/3 day (cleavage stage) embryos. Therefore growing embryos to the blastocyst stage allows us to select embryos that are developmentally competent which means they have a higher chance of resulting in a pregnancy.
There has been significant discussion regarding the best time to transfer embryos back into the mother and whether it is better to transfer the embryos earlier (day 2-3) or to wait and transfer embryos at the blastocyst stage (day 5-6). In an IVF cycle the embryos are transferred back into the mother’s uterus, which is the location an embryo reaches in a natural pregnancy at the morula-blastocyst stage (day 4-5). In a natural pregnancy day 2-3 embryos are still in the fallopian tubes. The fallopian tubes and uterus are different organs with very different environments. Day 2-3 embryos require significantly more assistance in regulating themselves and rely heavily on the environment of the fallopian tubes which are designed to provide them with the correct nutrients. The uterus is designed to take an embryo only once it reaches day 4. This is another reason why Monash IVF prefers to transfer embryos at the blastocyst stage.Our advanced technology enables us to provide optimised culture conditions which mimic that of the fallopian tube to enable us to take care of your embryo and only transfer it at the right time in the right place to give it the best chance of becoming a baby.