The stage of the embryo implantation in the endometrium is the most critical part during the reproduction process. It includes a number of complicated signaling events, which will lead to a successful pregnancy. However, in many cases the embryo implantation in the endometrium does not proceed as expected. One of the reasons of this failure is whether the endometrium is ready for the embryo implantation. Typically, this happens on the 7th-8th day after the ovulation, a period which is also called “implantation window”.
In certain instances of women, the “implantation window” may differ leading to an unsuccessful embryo implantation. The purpose of this study was to analyze the endometrial receptivity by means of molecular techniques in women with repeated failed attempts and good quality of embryos in order to determine the “implantation window”.
In 20 women of average age 38.04 (Β± 3.9), an endometrial tissue was obtained seven days following the LH surge in normal cycle or five days after the beginning of administration of progesterone in a cycle with hormone substitution. The material was tested for the differential expression of 238 genes related to the endometrial receptivity. In the case of a negative result, the test was repeated with one additional day in order to provide a new assessment.
In total, in 5 women the test showed negative results, and, therefore it was repeated in order to determine precisely the right day for implantation. After retesting, a blastocyst embryo transfer was performed on the respective day (+6 or +7), where 2 out of 5 women showed positive results in term pregnancy.
The implantation of the embryo in the endometrium is a complicated process controlled by the synergistic expression of various genes and may only happen on specific days during menstruation. The β€implantation windowβ€ plays a major role in the outcome of the in vitro fertilization and, as a result, its determination is necessary with regard to incidents during which its occurrence is delayed.
Mary Rosa Mitropoulou, Vaia Gota, Sonia Teftsoglou and Theodosios Arkoulis, Mitosis Centre of Medically Assisted Reproduction, Piraeus