Well, usually the embryo implants in the blastocyte stage (between day 5 or 6) but the implantation on the endometrium begins on day 7 so, when we do an in vitro treatment, it depends if we are transferring a day 3 embryo or if we are transferring a day 5 embryo. If we are transferring an embryo on day 3, it will remain in the uterus for 3 or 4 days until it begins to implant. But when we do a transfer in day 5, it is at the blastocyst stage. It can proceed to implant at any moment but usually, it takes one or two days.
We don’t exactly know when embryos implant. We usually say that we believe that the implants 24 hours later but of course if you are doing a Day 3 embryo transfer, we know that the embryos do not implant on Day 3, they usually implanted the blastocyst stage which is Day 5 or Day 6, so Day 3 embryos, would probably float around in the endometrial cavity, in the uterine cavity for another 48 to 72 hours and then start implanting whereas blastocysts can potentially start implanting the same day as the embryo transfer or even 24 hours later but unfortunately, we don’t know when these events happen because there is no camera within the uterus to see when the embryo implants.
Embryos begin the implantation process once they reach the blastocyst stage, which occurs on days 5-6 after conception. If you have an embryo transfer on Day 2-4, the embryo will float safely in your uterus for a few days before hatching out of its protective shell and beginning the implantation process. If you have an embryo transfer on Day 5-6 the embryo should start to implant within a day or so of your transfer.
The implantation process involves the embryo hatching out of its protective shell and completely imbedding itself in the lining of the uterus, and this process can take up to a week for the embryo to complete.
Implantation depends on the day of transfer. Of course, if we transfer day three embryo, this embryo should be developed till the stage of the blastocyst. So it takes minimally two days, max. five, the embryo will be in the blastocyst stage, and then there’ll be implantation. So if we transfer five day embryo, a blastocyst, implantation can be directly after the embryo transfer, especially if the embryo is fully aged. I expect implantation on the same day of transfer, or maybe the next day.
Normally, we expect, according to the scientific studies, the embryo implantation two days after the embryo transfer day. Sometimes, they say that it can be up to five days, but normally, we expect it on the second or third day after the embryo transfer day. There will be no change in the physical symptoms. Patients usually do not feel anything.
A straight answer: yes, it can. And it is facilitated by two things: one is the stage of the embryo (which is day 5). Also, the embryos have started hatching. So if we have a blastocyst that started hatching, whether by assisted hatching or the cells have already come out of the shell of the blastocyst, this actually entails that the implantation is imminent. So as soon as we return it, the implantation should be within 24 hours.
The implantation does not take place immediately after the embryo transfer. It usually takes place between 24 and 36 hours we have transferred the embryo. What we do is that we gently release the embryos inside the uterine cavity, and then the embryos stay around there for these 24 to 36 hours. It’s quite common that patients ask us what they can do after the embryo transfer if that is going to have an impact on the implantation or not, in normal conditions not. For example, we request our patients to come with a full bladder, we let them go to the toilet after the transfer has finished, they can even travel on the same day the embryos are going to remain there because the uterine cavity is a virtual cavity, so there is no risk that the embryos may fall out after the transfer regardless of what you do. It’s a completely safe procedure, and it’s completely safe to start leading a normal life after a couple of hours.
Why do we recommend these two hours after the embryo transfer? It’s because they may help keep the uterus relaxed, and that’s the only thing that seemingly can improve the implantation rates. Basically, what we want is to keep this uterus relaxed until the embryo is implanted. If you want to take things easy for these 24 hours, that’s fine, it’s not going to be a problem, but it’s not strictly necessary.
In the end, we may think about what a woman does when she is trying to get pregnant naturally. I mean nobody spends one day at home after they have had sex just because they think that is going to improve the implantation rates. They keep leading a completely normal life, they even go to the gym, they may have a glass of wine and things like that if the embryo implants, it is going to implant anyway. Don’t get too stressed about what you can’t do after the embryo transfer and especially in the first 24 hours that you need that are going to pass before the embryo implants.
