What causes implantation issues with IVF with own eggs or with donor eggs? What are the signs of embryo implantation issues? And what are the symptoms of implantation issues an IVF patient may have? Watch the webinar and check the answers to these questions. The entire webinar was dedicated to the topic of “Implantation issues and hormonal reproductive defects”.
Implantation and hormonal issues
Embryo implantation is a complex process
, which involves many different factors. In cycles of IVF, where an embryo fails to implant, it can be heart-breaking and confusing, leaving patients asking why and how? In this webinar, Dr Alexandra Izquierdo, medical director of ProcreaTec International Fertility Clinic, Madrid, Spain, discusses what implantation actually means, and the different elements required in order for an embryo to implant and continue to grow, into pregnancy and live birth.
“Implantation is the last frontier in assisted reproduction”, said pioneer of in vitro fertilisation, Dr Robert Edwards, and when thinking about IVF, it really is the final hurdle, following hormone injections, fertilisation and the creation of a, hopefully, healthy embryo.
Implantation must happen, in order to create a pregnancy, yet, sadly, even after IVF, implantation is not a given, even with a top-grade embryo. Of course, having a good quality embryo is key and each day an embryo survives, in a laboratory situation, embryologists are able to garner further information, about its viability, providing increased knowledge as to which embryo/s will offer a higher chance of implantation. Pre-implantation genetic screening (PGS) also enables greater insight into embryonic health.
However, alongside a good quality embryo, there are many other factors which can affect whether, or not, an embryo will implant.
Implantation happens when the outer shell, of the embryo, attaches to the cells of the uterine lining, it’s therefore incredibly important that a woman’s body is well prepared, for the transfer; her hormones have to mirror and be in synch with what would happen, during a natural cycle, creating, what Dr Izquierdo describes as; “the window of implantation”.
For a pregnancy to occur naturally, the female body goes through various hormonal changes to prepare for receiving a fertilised oocyte (egg). Ovulation (the release of the egg) occurs, typically monthly, and the hormone oestradiol is produced; oestradiol is the main oestrogen found in women, and one of its functions is to induce the endometrial lining to thicken, preparing itself for the attaching of an embryo. If an egg is fertilised, during a natural cycle, and implants, the newly pregnant body then enters, what is referred to as, the luteal phase, whereby the corpus luteum naturally produces the correct amount of progesterone, required to support early pregnancy. Progesterone stimulates the growth of the blood vessels, which supply the uterine wall, and stimulates glands, in the endometrium, which then nourish the early embryo, helping it to become a viable, ongoing pregnancy. All of which needs to be replicated, when undergoing assisted conception; if there is a hormonal imbalance or thinner uterine lining, then an embryo is likely to struggle with implantation.
Implantation and hormone levels
Dr Izquierdo explains that in situations where hormone levels are not where clinicians would want them to be, and in cases of OHSS (Ovarian Hyper Stimulation Syndrome) a frozen cycle may be suggested, so that doctors can ensure the correct hormonal balance for a transfer. A similar protocol tends to happen with women using donor eggs and/or embryos, who should also be monitored, and undergo hormone tracking, before the transfer takes place.
It’s important to remember that every person is unique and therefore it’s the duty of clinics to provide a tailormade service for each individual; the window of implantation isn’t necessarily the same for all patients, and the transfer needs to be carefully timed around each woman. As vitrification (freezing) processes are much improved, it means that medical teams now don’t have to take the risks a fresh transfer may produce; if the hormonal profile is not in the correct state, the transfer can take place during an alternative, natural or medicated, frozen cycle.
Blood flow and immunology
Another factor, which is thought to affect implantation, is blood flow and immunology.
This is, currently, a rather controversial subject, in which many studies are taking place. Dr Izquierdo advises that the issue, with testing in this area, is that, as of yet, it’s difficult to produce any clear or fully conclusive results.
However, it is known that the implantation process requires good blood flow, to the uterus, so that the embryo can implant and continue its development, inside the endometrium. For women with recurrent implantation failure or miscarriage, Dr Izquierdo does recommend testing for thrombophilia (blood flow disorders), stating that, although limited, studies are being conducted, into blood flow, and data is showing that when embryo aneuploidy (embryo anomaly) is ruled out, thrombophilia could be to blame, for implantation failure.
There is also some controversy surrounding NK (Natural Killer) cells testing, but, again, Dr Izquierdo advises it’s worth testing in women with recurrent implantation failure and miscarriage.
NK cells are thought to kill the outer shell of the embryo, thus making implantation impossible.
If a patient tests positive, for NK cells, then there are possible treatments, which can be suggested, to see whether the chances of implantation and ongoing pregnancy, can be improved.
Whilst embryo quality is the main factor responsible for implantation, it’s important to remember that it’s not the only determinant.
Uterine and hormonal health is of great importance too and, whilst some tests may currently not be conclusive, more studies are taking place, and data is being collated, so that medical scientists can improve their knowledge and further understand how to help healthy embryos implant. Each patient is unique and personalised treatment truly does play a huge role in the final frontier, of IVF.