What happens to the Embryo inside the body after an Embryo Transfer?

Once the embryo transfer is complete, it usually takes about nine days for the detection of pregnancy. In the ensuing period between the completion of the embryo transfer and the detection of pregnancy, the embryo goes through a wide range of changes.

On day one the blastocyst begins to hatch out of its shell, and this continues into day two wherein the blastocyst begins to attach itself to the uterus. Progressing into day 3, the blastocyst is attached deeper into the lining of the uterus and the implantation begins. On day 4 the implantation continues, while its completion occurs on day 5. The cells by this time have become the placenta and the development of the fetus also commences by this time.
It is on day 6, that the human chorionic gonadotropin hormone starts to enter the bloodstream, and it is now possible to detect the pregnancy. Although, the traces of it at this point are rather low. As the fetal development continues, on day 7 and day 8 the hCG is adequate enough to be secreted.

Finally, by day 9 the hCG levels are high enough to be adequately detected in the bloodstream and a pregnancy test can be conducted to ascertain pregnancy conclusively.

Also, during the period between the embryo transfer and pregnancy test, certain symptoms similar to menstruation may be common. These include – bloating, fatigue, mood swings, soreness of the breasts, muscle cramps, and some light spotting.