3rd week of pregnancy: how the fetus develops and what happens in the body

Second obstetric week pregnancy ends with the long-awaited conception. During these days, the egg and sperm join together and form the first cell of the embryo. This means that the third obstetric week of pregnancy is the first week of development of the unborn child. What happens this week in the female body.

Signs of pregnancy at 3 weeks

Usually, in the third week of pregnancy, a woman is not yet aware of its actual onset. On the contrary, at this time she waits for the appearance of menstruation. Doctors say that no external signs of pregnancy are visible at this stage.

However, a woman’s feelings can change dramatically during this period. The reason for this is a sharp jump in the levels of estrogen and progesterone in the blood. And although the symptoms of pregnancy may be different for each woman, the following are most often observed:

• The mammary glands become more sensitive.
• Appetite changes, new taste needs appear.
• Basal temperature increases.
• The woman is very tired.
• The urge to urinate occurs more often.
• Your mood may suddenly change.
• A woman begins to perceive odors more acutely, especially harsh ones.
• A woman may experience intestinal upset. Under the influence of progesterone, the intestinal muscles relax.
• Some women may experience morning sickness.
• Sometimes there is slight bleeding smear about character. The reason for this is the fixation of the embryo inside the uterus. Usually such discharge is very scanty and not painful.

Belly at 3 weeks pregnant

A woman still perceives all the symptoms and characteristic features of pregnancy as harbingers of the onset of menstruation. Indeed, every time before menstruation, the breasts become more sensitive, the mood changes, and the lower abdomen ache a little. However, not all women experience this last symptom. And many ladies simply attribute indigestion to low-quality products.

Only ladies who consciously planned a pregnancy can guess about the current state of affairs. The rest are confident that menstruation is about to begin.

If at this time you perform an ultrasound with a special transvaginal sensor, you can detect the presence of pregnancy and accurately determine the place where the fertilized egg has settled. At such an early stage, an ultrasound is necessary only to make sure that there is a pregnancy, and also to make sure that it is not ectopic. The embryo itself will not yet be visible on the screen, but it will be possible to see the thickening area in the endometrium.

During this period, it is necessary to continue to eat properly and maintain moderate physical activity. Sometimes a woman in the third week feels increased sexual arousal, and maybe the opposite reaction - you want peace.

Fetus at 3 weeks of gestation

Just a few hours after fertilization, the egg, now called a zygote, begins to divide. The size of the zygote does not change. First, two cells are formed from one cell, and after a day there are already four of them. Then the division accelerates and occurs in geometric progression. As a result of this division, the zygote turns into a morula in three days. Outwardly, it resembles a mulberry. At this moment, the size of the unborn baby is only a tenth of a millimeter.

The third week of pregnancy also makes adjustments to the structure of the ruptured follicle. In its place, the so-called yellow body appears. This object received this name due to the coloring of its fabrics. The hormone progesterone is formed in the corpus luteum, which helps pregnancy develop and prevents the expulsion of the fetus from the female body.

If the future embryo successfully attaches to the inner surface of the uterus, the corpus luteum continues to function. Until the placenta is formed, the corpus luteum is responsible for maintaining the pregnancy. The placenta then takes over these responsibilities. If the fertilized egg is not fixed, then the corpus luteum begins to degrade and soon transforms into a white body, and then disappears altogether. If you do an ultrasound these days, you can see a corpus luteum in one of the female ovaries. This temporary female organ produces progesterone. Under the influence of this hormone, a woman’s immunity weakens. This is necessary to maintain pregnancy. The fact is that the fertilized egg is still perceived by the mother’s body as a foreign body that needs to be expelled. Progesterone reduces immunity and prevents getting rid of the fertilized egg.

By the end of the third week of obstetric pregnancy, the fertilized egg tries to strengthen itself on the walls of the uterus. Having reached the uterus, the fertilized egg begins to penetrate its wall. All this time, the cells of the fertilized egg are still dividing intensively. In this case, the outer layer of cells will subsequently become the placenta. And the inner layer will form the child’s organs.

This indicates that the implantation period in your pregnancy has begun. This is actually a very important week. You could say this is a critical moment. If implantation is successful, the pregnancy continues and the baby develops further. But at the same time, it is often during the third pregnancy that abortion occurs. Then the bleeding starts. Often a woman may not even suspect that she was pregnant.