4 week of pregnancy

At 4 weeks of gestation, implantation of the fetal egg in the wall of the uterus continues and the formation of the embryo begins, which will soon turn into a fetus, and then into a newborn baby.The future mother does not yet know about the new life developing within her, but very soon both the pregnancy test and ultrasound will yield positive results.

Table of contents: What is implantation?Human chorionic gonadotropin Maternal sensations at 4 weeks gestation Fetus at 4 weeks of pregnancy Possible problems Recommendations for mother at 4 weeks of gestation Recommended reading:

What is implantation?

Normally, the fertilization of an egg with a sperm occurs in the fallopian tube.On the way of the fetal egg from the uterine tube to the uterus takes an average of 6-7 days.Once in the uterine cavity, the fetal egg( at this stage it is called the blastocyst) adheres to the inner uterine membrane( endometrium) and starts to secrete the enzymes necessary for deeper penetration into the uterine wall.This is implantation.

In the process of implantation, the trophoblast( formed from the outer cells of the blastocyst) begins to actively divide and transform into a kind of villi, which gradually penetrate into the depth of the endometrium.With these villi, begins the formation of villus chorion - the structure responsible for providing the embryo with all the necessary substances until the appearance of the placenta.

Lacunas filled with maternal blood form around the villi of the chorion, from which a developing small organism draws oxygen and resources for active growth.

Implantation of the fetal egg in some pregnant women is accompanied by a small discharge of blood from the genital tract - the so-called implantation bleeding .Its appearance is associated with the destruction of the walls of the vessels of the endometrium under the action of enzymes released by the trophoblast.Gynecologists consider this phenomenon as a variant of the norm, but only if it is repeated only once and is not accompanied by strong painful sensations.

Human chorionic gonadotropin

After implantation of the fetal egg cells of the developing chorion begin to synthesize a specific hormone - human chorionic gonadotropin( hCG) .This substance by activity against the reproductive organs of a woman at times exceeds sex hormones.

The main function of HCG is to force the female body to reconstruct itself to preserve and maintain the life that has arisen.Under the influence of hCG, the synthesis of progesterone( pregnancy hormone) is increased, stress resistance is increased and a number of other important processes occur.

Detection of hCG in body fluids is used to diagnose pregnancy. Normally, a few days after implantation at a concentration sufficient to determine by available methods, hCG appears in the blood, and in urine only in a week, so even the most sensitive test can give an accurate result about the presence of pregnancy not earlier than 2 weeks afterConception.

Each pregnancy has its own concentration of hCG in the blood, which gives doctors the opportunity to assess how correctly pregnancy takes place.For example, low rates of increase in hCG are characteristic for ectopic pregnancy, and a sharp decrease in the concentration of this hormone is for a threatening or already occurred miscarriage.

Mom sensations at 4 weeks gestation

At 4 weeks of gestation, a woman begins to feel the swelling of the mammary glands and the increased sensitivity of the nipples. Besides this, the expectant mother becomes more irritable, emotionally unstable, quickly tired and constantly wants to sleep.The body weight may increase slightly( from 0.5 to 1 kg).

The appearance of these signs is associated with the effect on the female body of progesterone.In principle, the same substance is synthesized by the yellow body of the ovary in the second half of the menstrual cycle in the absence of pregnancy.Therefore, many women have symptoms such as irritability and swelling of the chest, occur before every menses and they can not be regarded as the first signs of pregnancy, if there is no delay.

Fetus at week 4 of pregnancy

This week, from the clusters of cells called the blastocyst, embryo and extra-germline structures( chorion, yolk sac, amnion) begin to form.

The cells of the embryoblast( inner blastocyst) are divided into two populations at week 4:

• The endoblast, from which the yolk sac forms.
• Ectoblast is a precursor of the amniotic cavity and amniotic fluid.

From the cells located at the junction of the endoblast and the ectoblast the embryo embryo begins to form. At 4 weeks of gestation, the future embryo consists of only three layers( leaves) of cells that differ in structure:

• Ectoderms.This leaf will give rise to skin, hair, eyes, nervous system, tooth enamel, baby's ears.
• Mesoderms are the future muscles, skeleton, blood vessels, heart, kidneys of the baby.
• Endoderms are the precursors of the digestive system, lungs.

Fruit egg by the end of 4 weeks of pregnancy is no longer called blastocyst, but gastrula, and the stage of intrauterine development of the baby is gastrulation. The embryo size at this stage is only about 1 mm ( this is less than the poppy seed).

Possible problems

4 week of pregnancy, like 3, is a critical period of the intrauterine development of the baby. The embryo is extremely sensitive to the negative effects of radiation, chemicals, drugs, infectious agents, especially since he has already established a connection with his mother, so practical everything good and bad that is in her blood is transmitted to the child.

In addition, 4 weeks can be called decisive in terms of immediate prospects.If there was an implantation and embryo development began, the pregnancy will continue.If the fertilized egg for some reason could not penetrate into the endometrium or the embryo formation has not begun, the woman will have another menstruation( possibly with a slight delay) and the fetal egg will come out together with the menstrual secretions.And the woman does not know about it.

There are many reasons for the death of a child at such an early time.Most often, these are gross developmental disorders, which at this stage are called blastopathies.In addition, the unevenness of the endometrium or uterine abnormalities may prevent the normal implantation of the fetal egg.Their role can play and immune disorders, due to which the body of the mother simply rejects the alien object in the person of the embryo( normally in the female body, immediately after fertilization, an early pregnancy factor begins to be released, which suppresses the immune response and thereby helps to preserve the child).

Recommendations for mother at 4 weeks of gestation

The life style of a woman this week largely determines how the development of the tiny creature inside her will and will be.Therefore for the expectant mother is very important :

• Do not take any medication without doctor's prescription.And in conversation with the doctor it is necessary to mention that pregnancy is possible.
• Do not undergo an X-ray examination, CT, MRI, and other studies that are contraindicated in pregnancy.
• Completely eliminate bad habits.
• Do not contact infectious patients and animals.
• Protect yourself from the negative impact of harmful chemicals( the same household chemicals) and, if possible, factors of the work environment, if any, in the workplace.
• Avoid overwork and stress.

The future mother should fully eat, drink vitamin complexes( if they were prescribed by a gynecologist), walk in the fresh air, do something pleasant for the soul, communicate with loved ones and experience more positive emotions.

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Zubkova Olga Sergeevna, medical reviewer, epidemiologist