Actually, if we are transferring a day 5 embryo, it will take about 48 to 72 hours for the initial implantation. Of course, there are a lot of things that the embryo has to do to actually implant. We expect that because between day 5 and 6, they do the hatching and they can get in touch with the endometrium cells and start doing the procedure. So, I would say around 48 to 72 hours we should probably have some news on implantation.
Implantation will happen at some point around the 7th to 8th day of embryo development so normal implantation happens at some point at around the transfer because at day 6 an embryo is trying to escape from what we call the zona pellucida and is the time at which the embryo will have some dialogue with the endometrium to go into the endometrial so that’s what we call the implantation.
We know that happens at some point after the hatching of the embryo.
This is a very interesting question, very scientific. So the answer is, the implantation very much depends, or the time of the implantation very much depends on the age of your embryo. If you have an embryo that is a fully developed blastocyst, which is a day 5 grown embryo, then, we have seen from our experience, that when we transfer a blastocyst, it has already started to hatch from the shell.
From the moment it hatches, it will take 48-72 hours for it to implant. So the embryo implantation is not happening at the same time as the embryo transfer. The embryo is transferred inside the uterus, and when it hatches from the shell, it starts digging and implanting. That process usually takes, as I said, between 48-72 hours in a fully expanded blastocyst.
If you have a day 2 or day 3 embryo, they are just a little bit behind in terms of staging. Then, obviously, they have to carry on developing. They have to become blastocyst first. You have to add those extra 2-3 days to the implantation time. That is also guiding us on the best time for the pregnancy test. But yes, the answer is that the embryo is not implanting at the same time as the embryo transfer, it will happen subsequently.
If we transfer a day 5 embryo blastocyst, it takes up to 24 hours, not more. If we transfer an embryo at a low stage, day 2 or day 3 embryo, the embryo needs some time for development, and then it can be implanted. It needs two or three days. A blastocyst needs 24 hours.
During natural conception, the first four or five days of development are in the fallopian tube, and then the embryo sticks to the uterus. So we do the same thing, we transfer the embryo at the same stage as it is implanted during natural conception.
If you transfer two day embryo, the embryo is waiting in the uterus for the stage at which implantation is possible. A three day embryo cannot be implanted, it should be a blastocyst. Only a blastocyst is able to go through the cells inside the endometrium. My opinion is to wait till day five because you are sure that the embryo is developed till day five, and if the development stops, it’s also valuable information for the patient.
According to scientific studies, we can expect the embryo implantation in two days after the embryo transfer day. During this period, the patient won’t feel any change in her body, and maybe sometimes according to other studies, the implantation can happen on the fifth day but normally, according to our knowledge, it’s two to three days after the embryo transfer.
This question obviously depends on the stage of an embryo. We have two stages at which we do the embryo transfer: day 3 or day 5. We used to do the transfer on day 2 or day 3 – now things have evolved very quickly and the recommended date is day 5. Why? Because we have the blastocyst which has the highest implantation potential. We know that implantation usually happens on day 5. If in a normal pregnancy, by the time sperm fertilised the egg in the fallopian tube until it moves around the fallopian tube and goes into the uterine cavity, the implantation procedure starts and the embryo is embedding itself into the endometrium – then we are arbitrarily saying that the implantation happens around day 5 or day 6. So if we are transferring a blastocyst, the implantation is expected to be within 1 to 2 days. However, if you are transferring an embryo on day 3, it will obviously happen at a later stage. Regarding the embryos which are frozen on day 6, after thawing and transferring them, we should expect the implantation to happen very soon as well. So do we need to do anything in particular to help the implantation? No, this is a natural process, the embryo is all ready on day 5, so we are just waiting for the endometrial interaction with the embryo to facilitate the implantation.
The implantation does not take place immediately after the embryo transfer. What we do in an embryo transfer is that we gently release the embryo inside the cavity using a medium specially designed for keeping the embryo alive, and then the embryo remains there for between 24 and 36 hours. The real implantation takes place between day 6, day 7, after the egg collection.
It’s quite common that patients ask us what they can do after the embryo transfer because they just try to improve or make it easier for the embryo to facilitate the implantation. In fact, there’s nothing patients can do, and as I always say, I give the example of a woman who gets pregnant naturally and well these women do not usually do anything special, they just live a completely normal life, they don’t stay at home, don’t stop doing things, go to the gym, have their glass of wine whenever they want, or things like that. Don’t get too stressed, the embryos are not going to fall out even if you go to the toilet right after the transfer, even if you move, or even if you take a plane, and you fly back to your home. This endometrium cavity is virtual, and the embryos remain there until they implant or not.
