Dear expectant parents, understanding how a spontaneous pregnancy occurs is a basis for understanding the causes of infertility. In this section, I will explain how pregnancy occurs.
In the ovaries, egg cells are stored in a special structure we call follicle. Follicle consists of the female egg cell, that is, the oocyte, the support cells that support the oocyte immediately around the oocyte, and the follicle wall at the outside, which protects the egg from external influences. At puberty, there are approximately one million follicles in each ovary. At the beginning of each menstrual period, a certain number of follicle cells from each ovary are selected to grow that month. Only one of these selected follicles will grow sufficiently and the egg cell in this follicle will be fertilized by the sperm.
While the number of follicles selected to grow during each menstrual period is higher at younger ages, this number increases with increasing age. It begins to decrease.
At the beginning of the menstrual period, only one of these follicles containing egg cells can be used. When the other follicles are not used, they will melt together with the egg cells inside and cannot be used again. Since there is no new egg cell production in the woman since birth, the number of follicles in the ovary will continue to decrease each month. In other words, more than one egg is actually spent every month to mature one egg. There are no follicles left in the ovary after being wasted, and therefore the absence of egg cells is called menopause.
Beginning of the Menstrual Period
The race is on. Are you ready for the race, ladies?
Follicle stimulating hormone, that is, FSH, secreted from the brain, gives the command to the race-ready follicles in each ovary to start the race. FSH is the nutrient necessary for the growth of follicles. Follicles begin to compete to use this nutrient. The follicle that uses the FSH hormone best starts to get ahead of the others and grow faster. As the follicle grows, the number of support cells that nourish the egg begins to increase and fluid accumulates within the follicle. This increases the volume of the follicle. The diameter of the follicle, which is 5-6 mm at the beginning of the menstrual period, disappears with fluid accumulation. k increases and reaches 17-20 mm. Other follicles that cannot use this chance gradually slow down and leave the race. Now the single follicle is left alone in the race.
The time has come to leave the follicle: Oh separation, terrible separation...
The increasing number of support cells in the follicle nourish the egg cell and prepare it for fertilization by the sperm. Of course, the follicle cannot grow continuously. Now it is time for the ready egg cell to separate from its friends. The follicle must crack and the egg cell inside must pass into the fallopian tube. We call the rupture of the follicle ovulation or ovulation. The signal for the rupture of the follicle is given by the LH hormone, also produced by the brain. Thus, the egg cell leaves the follicle and immediately passes into the fallopian tube located in close proximity to the ovary, and the egg cell is now ready to be fertilized with sperm. Ovulation time is not the same for every woman. Not every woman's follicle growth rate is the same. Every woman is created with different characteristics. For a woman whose average period is 28-30 days between the 1st day of her two menstrual cycles, the middle period of the menstrual period, approximately days 14-15 from the 1st day of the menstrual period, is the ovulation time, although it is not certain.
Is There Anybody? I'm so bored...
Yes, the egg has now passed into the tube. After the egg passes into the tube, the chance of fertilization with sperm is approximately 24 hours. If fertilization does not occur within this period, there will be no chance of pregnancy for that month. If we assume that the average lifespan of sperm in the female genital system is 48 hours, intercourse within 24 hours before ovulation and 24 hours after ovulation is very important for pregnancy. This is why sexual intercourse at the right time is very important for pregnancy. Couples who have a healthy sexual life (on average 3 times a week) will be able to get this chance.
The egg cell begins to roll towards the uterus with the movements of the tube. After intercourse during this period, the sperm pass through the vagina, first into the uterus, and from there into the tubes, and make their way to the egg. The cervix acts like a filter. It only allows the passage of motile sperm. Sometimes even normally motile sperms may not be able to enter the uterus.
Men. Considering that there are approximately 20 million sperm in the human body, the number of sperm that can reach the egg after sexual intercourse is only 500. Only one of them will be able to fertilize the egg.
The First Meeting…
The sperm that reach the egg begin a race to make the egg like them. Once the sperm reach the egg, fertilization is not an absolute guarantee. For this reason, not every intercourse may result in pregnancy, even during the ovulation period. For this reason, if the woman is young after stopping protection, it is recommended to wait 1 year.
Provided that there is a regular sexual life after stopping protection, 8 out of 10 couples reach their pregnancy goal within 1 year. However, out of these 8 couples, some become pregnant in the first month, some in the 3rd month, and some in the 6th month. As you can see, even if there is no problem, pregnancy may not occur in the first month you stop using contraception.
Here is That Miraculous Moment...
One of the sperms around the egg, accepted by the egg, penetrates the egg membrane and reaches the inside of the egg. The membrane of the egg hardens and no longer allows any other sperm to enter the egg. We call the sperm penetrating the egg cell membrane and entering the egg and the information contained in the nucleus of the sperm merging with the egg nucleus, where the genetic information of the egg cell is stored, as fertilization, that is, in medical terms, fertilization.
Zygote is formed by the union of the nuclei of the sperm and egg cells. Zygote is formed inside the tube. While the zygote rolls towards the uterine cavity where it will settle, cell division begins. When the zygote starts cell division, it is called Embryo. While cell division continues in the embryo, it literally rolls towards the uterus. Approximately 5 days after fertilization, the embryo completes its journey in the tube and reaches the uterine cavity, that is, the uterus, and first attaches to the most suitable area there. The embryo, which attaches itself to the uterus and begins to receive nourishment from the mother's bloodstream, begins to produce pregnancy hormone. The pregnancy hormone ensures the production of pregnancy hormone from the ovary, which supports the pregnancy. In the pregnancy test performed on the blood, this is what we call B Hcg. We measure this hormone.
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