How is the implantation of the embryo in the case of IVF?

The implantation of the embryo is a key step: it is with it that the pregnancy really starts. Although in vitro fertilization techniques (IVF) can not directly ensure embryo implantation, they can however promote it ...

Do not confuse embryo transfer and embryo implantation

  • IVF requires extensive preparatory work (eg, ultrasound checks, injections to stimulate ovulation). In general, oocyte retrieval and sperm collection take place on day 27 after the start of injections (1st day of menses). It is from here that the true "in vitro fertilization" is carried out: oocytes and spermatozoa are brought together in a culture medium.
  • Usually, several oocytes are fertilized through this process, giving rise to a number of embryos.
  • Embryo transfer usually takes place 3-6 days after: the embryo (s) are transferred to the uterine cavity. On the other hand, the medical team can not directly implant an embryo in the uterine wall.
  • In practice, the transferred embryos evolve a few days in the uterine cavity before implanting themselves (or not) in the lining of the uterus, the endometrium. We are talking about implantation of the embryo or implantation, from which the pregnancy will really begin ...

How to promote implantation of the embryo?

  • For the implantation of the embryo to take place, several factors must be brought together (viable and sufficiently developed embryo, endometrium ready to receive it). However, the exact mechanisms of pregnancy still retain their mystery: even when all the factors are in place, the implantation of the embryo does not occur.
  • Anyway, at each IVF, the medical team does its best to boost the chances of embryo implantation. For example, it is common to implant two or even three viable embryos at the same time, in the hope that at least one of them will implant.
  • Of course, this also increases the chances of multiple pregnancy: this is why we rarely implant more than three embryos at the same time. Other embryos may be frozen for next transfer (if the first IVF fails or if the couple plans to have another child later using this technique).
  • In addition, medications may also be prescribed to ensure that the endometrium is sufficiently developed to accommodate the embryo. Several treatments are possible, in particular that based on micronized progesterone. The latter can be taken orally but it is more often prescribed in the form of vaginal eggs. Usually, this treatment should be followed for 10 to 12 days, until the blood test for the hormone beta HCG (human chorionic gonadotropic hormone): as for all pregnancies, it is this dosage that will reveal whether you are pregnant or not .
  • If necessary, another IVF may be attempted in the majority of cases. Many couples using this assisted procreation technique are successful in having a child.