3 weeks pregnant: how the fetus develops and what happens in the body

Second obstetric week pregnancy ends with a long-awaited conception. These days, the egg and sperm come together to 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 does not yet know about her actual coming. On the contrary, at this time she is waiting for the appearance of menstruation. Doctors say that no external signs of pregnancy are visible at this time.

Yet a woman's feelings can change dramatically during this period. The reason for this is a sharp jump in the content of estrogen and progesterone in the blood. And although the manifestations 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.
• The basal temperature rises.
• The woman gets very tired.
• More often there is an urge to urinate.
• Mood can suddenly change.
• The woman begins to perceive smells more sharply, especially harsh ones.
• The woman may have an intestinal disorder. Under the influence of progesterone, the intestinal muscles relax.
• Some women may have morning sickness.
• Sometimes small spotting begins spotting about character. The reason for this is the anchoring of the embryo inside the uterus. Usually such discharge is very scanty and not painful.

Belly at 3 weeks of pregnancy

A woman still perceives all the symptoms and characteristics of pregnancy as harbingers of the onset of menstruation. Indeed, in fact, every time before menstruation, the chest becomes more sensitive, the mood changes, the lower abdomen aches a little. However, not all women experience the latter symptom. And many ladies simply attribute indigestion to low-quality products.

Only ladies who deliberately 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 an ultrasound is made with a special transvaginal sensor, then it is possible to detect the presence of pregnancy and precisely determine the place where the ovum is fixed. At such an early stage, an ultrasound scan is necessary only to make sure that there is a pregnancy, and also to make sure that it is not ectopic. The embryo itself cannot yet be seen on the screen, but it will be possible to see the area of ​​thickening in the endometrium.

During this period, it is necessary to continue to eat right, 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 gestation

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

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

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

By the end of the third week of obstetric pregnancy, the ovum is trying to strengthen on the walls of the uterus. Having reached the uterus, the ovum begins to invade its wall. All this time, the cells of the ovum are still actively dividing. In this case, the outer layer of cells will subsequently become the placenta. And the inner layer will form the baby's organs.

This indicates that the implantation period has begun in your pregnancy. This is actually a very important week. We can say that this is a critical moment. With a successful implantation, the pregnancy is maintained and the child develops further. But at the same time, it is often on the third pregnancy that an interruption occurs. Then bleeding begins. Often a woman may not even be aware that she was pregnant.