In the 2. episode “pregnancy week by week,” we described ovulation and connection of the egg with the winning sperm of your partner. A new life and your pregnancy began. Our series will guide you through pregnancy week by week.
3 weeks pregnant
You are pregnant. Single-celled egg has joined with your partner’s sperm in the ovary and you are about to enjoy a period of joyful anticipation. Remember, however, that pregnancy brings many difficulties that you need to be ready for.
You have most likely no idea that you are pregnant even in the week 3. At this, time you are in the 3rd week of pregnancy from the medical point of view, although the germ of the baby is not older than seven days.
What happens in the week 3?
The egg is repeatedly divided after the fertilization. The first division is a split into two identical cells so called blastomeres, which happens in about 30 hours. Subsequent subdivision is already much rapid. Blastomeres are divided in geometric sequence. Each of these so-called cell cleavage division produces smaller and smaller cells. The process is called Cleavage division for how the embryo looks like. The germ is a cluster of 16 rapidly growing cells and is called a morula. It moves from the fallopian tube, where the fatal connection with the sperm happened, towards the uterine cavity. Morula is no longer a random cluster of cells in your womb. It has already been differentiated into an outer layer of cells which coats the inner mass of cells.
There are created first intercellular connections and some of the cells even communicate with each other. It means that they already exchange intercellular information even in such an early stage of pregnancy. Creation of these connections affects further development of the early embryo.
The morula changes into a pouch-shaped blastocyst in five days, the first working week of your womb. The outer cells begin to participate in the formation of the fetal part of the placenta. Inside the pouch there is located a cavity with fluid on a side. On the other side, there is a cluster of cells, the basis of an embryo of the baby. Blastocysts have developed without ties to mother’s tissues by now.
Week 3 is over
The 3rd week of pregnancy ends by creating connection between the embryo and you. You can proudly call yourself a future mother. The cover of the blastocyst, zona pellucida, completely disappears at the end of the 3rd week of pregnancy. The blastocyst attaches itself to the surface of the uterine lining with the part of the embryo.
The uterine lining transformed with increasing level of hormones and is now able and willing to accept the blastocyst and provide nutrition. The outer cells of the blastocyst produce again a large number of cells that implants the blastocyst in the lining of the womb, produce the enzymes that erode the uterine lining. The blastocyste burrows in the uterine wall which is also called nidation. It is mostly in the upper front part of the womb.
Your womb will be a home for your baby for another nine months. During this time, you will be able to gradually get in contact with your kind also through a series of ultrasound examination. Thanks to them, you will have images of your baby even before it is born.