On the 8th day of pregnancy, the implantation process continues: the blastocyst continues to implant in the uterine lining that it fully penetrates on the 9th day. The uterine epithelium then completely covers the implantation site.

At two weeks, the embryonic button has the shape of a sphere consisting schematically of two superimposed hemispherical cavities:

· The amniotic cavity which is formed by removal of the embryonic button and the trophoblast;

· The embryonic button, some cells of which form a flattened layer, and the blastocyst which takes the form of a disc made up of two layers: an internal layer and an external layer. We speak of didermic embryonic disc.

This second week is also marked by the start of the placement of the placenta, a platform for fetal-maternal exchanges. On the 9th day, the trophoblast (outermost layer of cells) divides into two layers of cells. In one of them will form small pockets called gaps. On the 12th day, small vessels in the uterine lining rupture and their blood then fills its gaps. These merge on the 13th day: it is the outline of the placenta and the establishment of the fetal-maternal circulation.

At the end of this second week of pregnancy, the egg measures approximately 0,2 mm.

The second week of pregnancy corresponds to 4 weeks of amenorrhea. The rules are expected at the end of the week, the mother-to-be still ignores her pregnancy.

Yet great hormonal upheavals have already started in his body. In the ovary, the corpus luteum – created from the rest of the follicle – produces large amounts of progesterone which ensures the proper implantation of the egg. The trophoblast produces the hormone hCG or pregnancy hormone which nourishes the endometrial tissue and keeps the corpus luteum active. The secretion of hCG will continue for 12 weeks, while the placenta takes over. It is precisely this hormone hCG that is detected in the pregnancy test.

This change in hormonal climate can cause various early pregnancy ailments such as nausea, swollen breasts, but very light and not always perceived by the mother-to-be.

If you are really impatient, you can do an early pregnancy test. These tests promise an effectiveness 4 days before the estimated date of the rules thanks to a higher sensitivity to hCG (10 to 12,5 IU / l), but their reliability is less, in particular because of the variations of the date of. ovulation and hCG hormone levels according to women. It is therefore better to wait a few days for your period to be late.

In the meantime, continue to avoid all risky practices: self-medication, alcohol and drug use, exposure to x-rays or chemicals.