One of the most exciting parts of your IVF cycle is embryo transfer. The moment your embryo settles and starts to grow following the transfer, your pregnancy journey officially begins. A competent blastocyst must interact with a receptive endometrium (uterine lining) for implantation to be successful.
What happens in the embryo transfer process?
The process of embryo transfer in IVF laboratories is done with the utmost care and precision, using the latest technologies and equipment available. Most clinics’ labs are generally specifically designed to provide an ideal environment for the creation and monitoring of your embryos.
Your fertility doctor will constantly strive to improve our methods to give patients the best chances of success. Embryologists use cutting-edge tools and artificial intelligence technology to select the finest quality embryos for transfer.
The chosen embryo will be treated to enhance the likelihood of implantation, before being carefully placed into the uterus using a delicate catheter, with guidance from ultrasound. All your transfer procedures will be carried out by a consultant. (1)
What happens after the embryo transfer?
Following the embryo transfer procedure, you have the freedom to move about. Your nurses will provide you with comprehensive instructions regarding the changes and experiences you may encounter in the following days, along with a list of necessary medications to support the growth of your pregnancy.
Nurses will inform you of the earliest date you can take a pregnancy test, which is typically two weeks after the transfer. (2)
What happens in embryo growth and implantation after the transfer process?
In the days following the transfer, your embryo starts to adhere to the uterine lining, and by day 5, it is typically implanted.
The insertion of the embryo and the start of fetal development trigger the release of the hCG hormone, which is what the pregnancy test picks up. By day 14 following the transfer, hCG levels are high enough to collect in your urine. hCG levels rise steadily each day. Therefore, while it may be tempting to test earlier, you may end up with a misleading result. (3)
How long does embryo implantation take?
After the blastocyst emerges from its shell, the actual attachment and invasion of embryonic cells begin within a day. About 10 days after egg retrieval, it can be called the last chance for the embryo to be implanted.
There appears to be some variation in the timing of implantation, depending on blood levels of the pregnancy hormone (hCG) and changes in ultrasound development at weeks 4 to 6 of pregnancy. However, in humans, there is not much room for movement for late implantation as the “window of implantation” is closed.
Implantation can sometimes be delayed. The reason for this delay is not yet clearly known. It may be due to slower-than-average embryo development or late development of uterine receptivity, or a combination of factors. (4)
How to improve implantation rates with IVF?
In the vast majority of cases, embryo quality difficulties rather than uterine problems appear to be the cause of IVF failure. Egg donation success rates, which are outstanding even for couples who regularly experience IVF failure using their own eggs, provide some support for this.
Do hormones have an impact on implantation? The uterine lining needs to be exposed to the ovarian steroid hormones progesterone and estrogen in sufficient quantities and at the right times to be receptive. (5)
Berkovitz, A., Eltes, F., Lederman, H., Peer, S., Ellenbogen, A., Feldberg, B., & Bartoov, B. (2006). How to improve IVF–ICSI outcome by sperm selection. Reproductive biomedicine online, 12(5), 634-638.