Embryo development by day after transfer with IVF

Women who are undergoing IVF treatment for infertility, as well as those who are just thinking about joining the protocol, are interested to know how the embryo develops after it is transferred into the uterine cavity. Embryo transfer is considered the final stage of the protocol, and after it, it remains only to wait for confirmation of pregnancy, if it occurs.

We will tell you about what happens to the embryo in this difficult and filled with anxiety and anticipation in this material.

About the beginning of life

From the moment when the sex cells of a man and a woman are at the disposal of reproductive specialists, a new and interesting stage begins. The egg must be fertilized. During in vitro fertilization, doctors can arrange for her to meet with the sperm in a special laboratory Petri dish, or they can carry out a more complex procedure - ICSI, in which a separate sperm is injected directly into the cytoplasmic fluid under the oocyte membranes.

Be that as it may, after a few hours, if fertilization has taken place, the embryological stage of your baby's life begins. The very next day after oocyte collection, a woman can find out the first results - how many embryos were obtained.

The embryos are placed in a nutrient medium, where they develop for several days under the supervision of an embryologist.

The doctor estimates the rate at which each fertilized egg is cleaved, which has already passed the zygote stage. The appearance of the cells, the thickness of the walls and intercellular membranes, the correct number of nuclei in the size of two are also important. As a result, at such an early stage, all embryos are divided into four categories:

Category A embryos (excellent quality);
Category B embryos (good quality);
Category C embryos (satisfactory quality);
Category D embryos (unsatisfactory quality).

Excellent and good quality embryos are recommended for transfer to the uterus. If it is not possible to obtain such embryos, as an exception, embryos of category C can be admitted to embryo transfer, but embryos of unsatisfactory quality for transfer are not recommended. The higher the category, the more likely the fetus is to implant.

On the second day after fertilization, the zygote has 2 to 4 blastomeres. Depending on the exact number, embryos receive their first "name" - they are designated as follows: 4B or 2C. If you are called such alphanumeric combinations, it means the following:

4B - received an embryo of category "B" and on the second day it already has 4 blastomeres;
2C - received an embryo of category "C" and on the second day it has 2 blastomeres.

There may be other options - 4A, 2A, 4C, 2B, etc. In any case, the number will indicate the number of blastomeres, and the letter will indicate the quality of the embryo. The best ones will be recommended for transfer to the uterus, which not only have a high category, but also split quickly enough, increasing the number of blastomeres.

The third day of embryonic development is considered decisive in many ways. By this day, the development of embryos with gross abnormalities in the genome usually stops spontaneously.

Doctors put embryos of "three days" into a woman's uterus only if the embryos are not of the highest quality, for example C. This is due to the fact that in the natural environment of the uterus the embryos will have more chances for further development.

On the fourth day, the zygote becomes a morula - this is a qualitatively new stage in the development of your future baby. Morula already consists of 10-16 blastomere cells. Outwardly, morula looks like a blackberry. If a woman becomes pregnant naturally, on the fourth day the morula may well enter the uterine cavity, or it may still pass through the mouth of the fallopian tubes.

A day later, on the fifth day, the morula becomes blastocyst. From this period, embryos are considered completely ready for implantation. It is for this reason that most often the transfer of viable embryos of good and excellent quality is usually carried out on day 5.

The decision on the transfer is made by two collegial doctors: an embryologist, who monitors the development of the embryo, and a reproductive specialist, who knows exactly the answer to the question of whether the woman's uterine endometrium is ready for the upcoming implantation.

In some cases, a later postponement is recommended, according to the combination of the testimony of these two specialists. However, “six-day” and “seven-day” embryos take root much worse.

On the 6-7th day of development, the embryo is already called gastrula. If it is in the uterus, implantation may already begin, since the gastrula membranes already secrete certain enzymes to dissolve the functional layer of the endometrium and penetrate into it.

After embryo transfer

The development of embryos after transfer may differ slightly, depending on the age of the embryo and favorable circumstances for its development. Let's look at all the options for embryonic development after the IVF protocol is completed.

"Three days"

The zygote, which is the fertilized egg at this moment, consists of 6-8 cells. Zygotes are inserted into the uterus using a soft and flexible catheter through the cervical canal of the cervix. It is advisable to carry out replanting at the end of the third day, since it is during this period that the so-called "developmental block" often arises - some of the embryos stop splitting and stop growing due to the presence of gross genomic abnormalities. It is the genome that "dictates" the rules of development. It contains all the information about which cells and how should divide, and subsequently differentiate.

If the quality of the germ cells was high enough, the chances of getting embryos with a complete genome are higher. But even in the case of the fusion of perfectly healthy germ cells (a normal oocyte and a high-quality sperm), they do not guarantee that some genomic abnormalities will not occur during fertilization. That is why it is important for the embryologist to make sure that on the third day of development, the embryo will not have a “developmental block”.

It is possible that development will stop after the transfer, but in this case, the reasons may no longer be genetic, but physiological: the endometrium was not ready to accept the embryo, the hormonal background of the woman is not favorable enough due to other factors.

So, the planting of the "three days" was made. During the first days after the transfer, embryos cannot gain a foothold, even theoretically, they "float" freely in the uterine cavity. The embryonic period of their development continues. The embryo transfer procedure itself does not affect the embryo in any way, if the procedure is carried out correctly. Zygotes are introduced into the uterus along with a small amount of the culture medium in which the cultivation took place.

The next day after transfer, the embryos in the uterus move to the morula stage. The forms of the embryo become smoother, the intercellular connections - more dense. At the end of the first day after the transfer, a hollow space appears inside the morula, it expands.

A process begins, which in embryology is called "cavitation": blastomere cells begin to divide into two parts. Each of the groups of cells will be entrusted by nature with its own mission, because very soon the intensive laying of organs and systems of the fetus will begin.

The second day after the embryo transfer procedure - "three days" corresponds to the fifth day of embryonic development. On this day, the morula becomes a full-fledged blastocyst. The cavitation process continues inside it, the cavity inside expands.

If the process takes place in favorable conditions, within a day after the onset of the blastocyst stage, the embryo will leave the expanded cavity and can begin the implantation process. If the conditions are not too favorable, the process can drag on for another couple of days or stop altogether, and then pregnancy will not occur.

The implantation process begins immediately after the embryo leaves the blastocyst cavity. The first stage is adhesion. The embryo simply sticks to the endometrium of the uterus. Immediately after this, its membranes begin to produce special enzymes that gradually dissolve the cells of the functional layer of the uterus. The embryo is "buried" in the endometrium, strengthens in it, this stage is called invasion. Both stages of implantation take 3-4 days on average. All this time, the process of cell separation by functionality in the baby's body does not stop, the number of blastomeres is rapidly increasing.

Thus, it is possible to speak about the completion of implantation after the transfer of three-day embryos only 6-9 days after the transfer. There is no norm, implantation can be later if embryos are transplanted in a cryoprotocol.

On the 6-9th day after the transfer, the embryo, which managed to implant, already produces chorionic gonadotropin: this hormone is produced by the chorionic villi, with which the embryo is attached to the uterus.

From the moment of attachment, your baby already receives oxygen and nutrients from the mother's blood. A full-fledged placenta will form at the site of attachment of the chorion by the 12th week of pregnancy.

"Five days"

Many of the processes described above, the embryo, which is five days old, does not take place in the mother's body, but in the nutrient medium in the laboratory. It enters the uterine cavity already at the blastocyst stage, ready to exit from its expanded cavity and the beginning of the implantation process. It is for this reason that day 5 embryo transfer is more common and considered more effective. In fact, the embryo immediately enters the uterus, which is ready to begin fixing within a few hours.

The next day after IVF transfer, the woman's uterus is not a blastocyst, but a gastrula, and with a favorable set of circumstances, adhesion has already begun. Two days after the transfer, the invasion process starts, and in another day, the implantation may well be completed. Although in the case of five-day-old embryos, late implantation is possible.

Every minute in a small organism (this is no longer just a set of cells and genes, but a full-fledged new life), the most important and intensive processes take place:

biochemical (production of enzymes, hormones by chorionic villi);
biophysical (cells continue to split, their differentiation according to their purpose is already beginning);
there is a metabolism (the baby is already feeding, receiving the necessary substances from mother's blood);
anatomical (the laying of the first organs begins, which still represent certain groups of cells, the first cells responsible for the formation of the heart are laid already 5 days after IVF).

Uterine period

An embryo or several embryos after implantation behave in approximately the same way and develop at approximately the same rate.

Two weeks after embryo transfer, a woman can already find out about her pregnancy: a blood test will show her, since hCG in the plasma will accumulate in sufficient quantities. 21 days after the transfer, you can and should do the first ultrasound.

All this time, the baby will grow rapidly. When the mother comes to donate blood, he will already have formed all embryonic structures without exception, and after another two weeks the heart will begin to beat, this touching moment can be experienced by doing an ultrasound at the end of 6 weeks of pregnancy (this will be exactly 4 weeks after embryo transfer).

The development of the crumbs by day after IVF actually repeats the entire evolutionary process, only the changes that have occurred to a person over ten thousand years, occur to your embryo in a day. A woman should understand that it depends on her lifestyle and compliance with the recommendations how successful the development of the embryo will be in the first days after replanting.

Recommendations

After embryo transfer, the woman receives a sheet or table of appointments and recommendations that will help her create the most favorable conditions for the implantation of babies (toddler). Of course, a woman cannot radically change something in the subtle cellular processes that occur inside her uterus. But it is obliged to create optimal conditions for achieving the effect.

Remain in bed for 1 to 2 days after transfer. Do not stay in bed for a long time, as this can lead to poor circulation to the pelvic organs.
Don't lift weights exclude intense training, running, jumping, any hard physical work.
Do not come into contact with chemicals, poisons, paints and varnishes, gasoline, acetone.
Eat balanced and adequate. A protein-rich diet is considered preferable after transfer.
Follow your medication regimen. After embryo transfer, progesterone therapy is very often prescribed. This is important in order to increase the chances of implantation and to maintain pregnancy as early as possible.
Beware of viral infections. If it's cold outside, take a sick leave (there is such a possibility) and exclude visits to large stores, markets, travel by public transport in order to minimize the risk of contracting influenza or SARS, which at this stage can have a fatal effect on the embryo, even if he will be able to implant.
Don't take any medication, if your doctor has not agreed to them. There are no harmless pain relievers or antipyretics. You must ask permission for any drug.

Don't have sex. With sexual arousal and the body, the smooth muscles of the uterus contract, the uterus becomes in tone, the intensity of the blood supply to the main female reproductive organ changes. The tone will most likely interfere with the implantation of the ovum.
Eliminate alcohol intake, do not smoke.
Do not be nervous. Calmness is of great importance, because stress hormones block sex hormones, and a normal endocrine background is the key to the success of the IVF protocol. Eliminate quarrels and conflicts, worries about pregnancy, you should not buy pharmacy tests and start testing within a day after embryo transfer. This will not give the correct result, but it will cause a serious psychological condition, which is now completely unnecessary.