Frequent urination is a sign of conception

3rd week of pregnancy

Pregnancy | Desire to have children | Get pregnant
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First things first so that there are no misunderstandings: Calculate the week of pregnancy by counting from first day of last period and not from the time of fertilization! This means that you are already in the 3rd week of pregnancy if fertilization was only a few days ago. It will be another week or two before your period stops. And only then does it make sense to have one pregnancy test perform.

There are women who instinctively know at this very early stage that they are pregnant. But most of them have no idea that something great is going on inside them: the creation of a new life has begun.

Your body reacts to its new task by producing various hormones, especially HCG and progesterone. In exceptional cases, these can be a few first in the next week (the 4th week of pregnancy) Signs of pregnancy cause - such as thatNo menstrual bleedingnausea, a suddenSensitivity to smell, frequentUrge to urinate(even at night!)Chest tightness and an inexplicable onefatigue.

What happens in the 3rd week of pregnancy?

One of the approximately 200 million sperm has reached the egg cell in the fallopian tube and within 12 hours of the ovulation fertilized. Then the outermost layer of the egg hardens so that no additional sperm threads can penetrate.

Occasionally, one or more additional egg cells can be fertilized by additional sperm in the same monthly cycle. This is how dizygoti arise Twins or multiple births. Identical twins are created when the egg cell that has already been fertilized splits, which can happen until implantation.



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Fusion of chromosomes after fertilization

Egg and sperm do not have a double set of chromosomes like the other cells in the body, but only half of them each. Instead of 46, XY (male) or 46, XX (female), there are only 23, X or 23, Y. So it happens that children get a random half selection of their genes from their parents, and that every child is different. And so it is understandable that the father's sperm determine the sex of the child. As sex chromosomes, they carry either an X or a Y with them, while the maternal egg cell always passes on an X. A fertilized egg cell with 46, XX becomes a girl, 46, XY becomes a boy.

As soon as the genetic material from the two parental halves has merged into a whole, the genetic characteristics of the child are determined. And that doesn't just refer to gender and eye color or facial features! Other hereditary predispositions such as height, physique, health and temperament are also contained in the "genome".

The fertilized egg moves to the uterus

The fertilized egg cell is only as large as a fraction of a millimeter. In its first week (i.e. during the 3rd week of pregnancy) it slowly migrates through the fallopian tube towards the uterus, supported by contractions of the fallopian tube and tiny filaments in it. It divides constantly on the way and therefore grows quickly. When it has arrived in the uterus, after three to four days, the individual cell becomes a small cluster of cells Morula (Mulberry) become. All cells contain completely identical hereditary factors in the cell nucleus and each could form a complete, identical person. This is also called omnipotence or totipotency, which plays an important role in the Stem cell therapy plays.

During the 3rd week of pregnancy, the morula looks for the right place in the uterine wall to implant itself. At the end of the week a fluid-filled cavity has formed in the morula, and the structure is now called the germinal vesicle or Blastocyst and consists of up to 150 cells that are already differentiating. The outer wall is called the trophoblast. A part of these cells become the Plaster cake (the placenta) andAmniotic sacThe skin, nervous system and brain develop from the other. The middle layer produces the skeleton, muscles and internal organs. And the inner accumulation of cells grows into the lungs and digestive tract.

The implantation of the blastocyst

No later than seven days after fertilization, i.e. at the end of the third week of your pregnancy, the blastocyst digs into the prepared mucous membrane of the uterus and lets it cover itself. This is called Implantation, nidation or nidation, and it can lead to a slight spotting, which is not infrequently considered to be the beginning of the menstrual period (so-called. Nidation bleeding). The outer cell layer, the trophoblast, establishes an initial connection to the maternal blood vessels during implantation.

Unfortunately, it can lead to a very early miscarriage (Earliest abortion) come when the embryo does not implant itself in the uterine wall at all. The most common reasons: The uterine lining was not prepared for implantation or the embryo showed serious disorders, e.g. chromosome defects.

Your pregnancy in numbers

  • 3rd week after the 1st day d. last period
  • 2 weeks + 1 - 7 days (medical calculation)
  • 1st week after fertilization
  • 1st - 7th day of embryonic development


Egg and sperm teamwork

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Frequently asked questions on the topic

Women who have already been pregnant often instinctively feel that the time has come again. And the first signs of pregnancy may appear before the pregnancy test shows a positive result. However, this is by no means a definite proof.

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About five to ten days after successful fertilization, the cluster of cells that will be born as a baby in nine months' time will have completed its implantation in the lining of the uterus.

Perhaps it is in this "digging in" to damage maternal blood vessels in the uterus ...

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In the first two to three weeks after fertilization, the dividing embryonic cells are still relatively resistant to damaging external influences, i.e. the embryo is either not damaged at all or so badly that it leads to a miscarriage (all-or-nothing rule ) ....

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From fertilization to the early phase of implantation in the uterus, i.e. in the two weeks before the absence of the menstrual period, the embryo still consists of relatively few and undifferentiated cells, so that a strong teratogenic (teratogenic) influence leads to early miscarriage ... .

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Folic acid plays an important role in all cell regeneration and cell division processes in the human body
Role. During pregnancy, a lack of folic acid can cause so-called among other things
Lead to neural tube defects in the child. In addition, heart defects, urinary tract defects and the ...

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Last updated: 11-05-20, BH