Now back to the issue of maturation of female germ cells, to know when a woman can get pregnant and when not. The monthly cycle, that is, the period from the first day of menstruation (always from the first day) to the first day of the next menstruation, is divided into two phases, separated by the egg maturation day and the days of menstruation: estrogenic (first phase, proliferation phase) and progesterone (luteal, second phase, secretion phase), depending on the production of certain female hormones – estrogen and progesterone. The second phase is always more stable and usually lasts 14-15 days. This stability is due to the fact that the egg was ripe at that time, and further, if it was not fertilized and the pregnancy did not occur, the female body quickly prepares for a new cycle, freeing the uterus from the old lining (endometrium) by its rejection in the form of menstruation. Therefore, when some doctors make a diagnosis of progesterone deficiency, it is often a very erroneous diagnosis, made only from a single blood test result. And many women “chew” progesterone, he is duphaston, he is urozhestan, he is the other names, believing that this particular drug will help them become pregnant.
You must understand that The second phase depends entirely on the quality of the first phase.. The first phase can be quite short, and vice versa, long, so the monthly cycle can normally be from 14 to 40 days, although most often we are talking about normal cycles of 21-35 days. There are no classic “little girl in my nose” cycles, when a woman menstruates every 28 days, in real life, because there are too many factors that influence the duration of the cycle. Variations of a cycle of 7 days on both sides are considered normal, or in other words, menstruation can begin a week earlier or later compared to the previous cycle. Many women cling to their heads and immediately run to a doctor in a panic if their menstruation was delayed by 2-3 days, or, on the contrary, started a little earlier. Thus, in the first phase, egg maturation occurs, which is located in the ovary in a special vesicle (follicle). Usually, several follicles begin to grow in both ovaries, but after the 7-8th day of the cycle, only one (rarely two) follicle grows further, so that between 13-16 days (on average, on the 14th day) to burst, which is called ovulation .
Often women mistakenly think that the ovaries work alternately. Many doctors often also have a very mistaken idea of the work of the female reproductive system. Two ovaries always work, and the growth of follicles with the onset of menstruation occurs immediately in both ovaries. And only approximately on the 7th day of the cycle (usually it is the 3rd day after the completion of menstruation) follicle growth begins to dominate in one of the ovaries, which will end with ovulation. But the ovaries continue to work, just as they did, because they need to get rid of those follicles that began to grow, but did not become dominant.
With ovulation, a mature egg cell, a female germ cell, ready for fertilization, extends beyond the limits of the ovary and ends up in the abdominal cavity., however, it is immediately “absorbed” into the fallopian tube, one end of which has a funnel with special processes. The egg cell is capable of fertilization in just 12-24 hours, and then it just dies and resolves if the baby was not conceived. So, couples planning a pregnancy should understand that the time when a baby can be conceived is very limited. If we consider that the egg ages from the moment of ovulation, and some may start aging before ovulation, the window of successful conception is very, very narrow.
Heading to the ampulla part of the fallopian tube (the widest), the female reproductive cell is exactly here that it meets with the male germ cells (spermatozoa), which begin to actively attack the egg, dying themselves at the same time, but not without a goal – as their contents dilute the thick wall of the egg. And then, finally, one “lucky” manages to get inside the egg, which practically absorbs it. The spermatozoon most often loses its tail in the process of conception. Thus, the statement that only one spermatozoon is enough to conceive a child is not quite accurate. Under natural conditions, there should be millions of actively motile spermatozoa, which play a very important role in conception, but the egg cell directly fertilizes only one spermatozoon. Next, the fertilized egg moves along the fallopian tube to the uterus, passing through several divisions – this is how the embryo appears. The process of this movement takes 4 to 6 days. Approximately 30 hours after fertilization of the egg by the spermatozoon, its first division occurs, on which the course and the whole pregnancy will largely depend. Scientists involved in reproductive technologies that allow artificial embryos to be created have found that if the very first division occurred poorly, unevenly, then the fertilized egg may be poorly quality, which will lead to poor implantation, and this pregnancy will in most cases end in its natural ( natural) interruption.
Cells that arise from the division of a fertilized egg are called blastomeres, and the embryo in this state is called a zygote. First, division occurs without the growth of these cells, that is, the size of the embryo remains the same. When the embryo has reached the 16-cell structure, its cells differentiate and increase in size. At this stage of the division, the embryo is called a morula, and in this state it enters the uterine cavity. The division continues and as soon as a fluid appears inside the morula, the embryo is called a blastocyst. Blastocyst contains primitive villi – chorion (hence the name hormone – “chorionic gonadotropin”), with which the implantation process begins in the uterus. What happens in the female body while the fertilized egg moves through the fallopian tube? Preparing the uterus to receive the ovum. If in the first phase the inner lining of the uterus, which is called the endometrium, increases (the cells divide and grow), then in the second half of the cycle, after ovulation, they are saturated with nutrients – this phase is also called the secretion phase, while the first phase of the cycle is called the phase proliferation. Although the thickness of the endometrium plays a certain role in the attachment of the ovum in the uterus, the quality of the endometrium plays a large role, which is achieved during the second phase of the cycle due to the increase in progesterone level. Many women run on endless ultrasounds to measure endometrial thickness. Normally, in most women of reproductive age, the endometrium is 5–8 mm thick (average).
And now we continue our journey through the female body not in the direction of movement of the fertilized egg, but talk about pregnancy hormones, or rather, about those substances that may appear in the blood and other fluids of women with the appearance of pregnancy. Very often women ask me what is their chance of getting pregnant during one month’s cycle? This question is related to another: how can you find out that a woman is pregnant? So, I remind you that the egg matures in the first half of the cycle, but while it is inside the follicle, fertilization is impossible. However, it is always important to remember that sperm can be in the fallopian tubes for up to 7 days and maintain fertility for up to 5 days. This means that the closer the sexual intercourse to the time of ovulation, the greater the chance of pregnancy. And since no one knows when exactly ovulation will occur – that is, the moment (not a period of time!) The release of an egg, then with serious planning of your pregnancy it is not worth speculating with a precise definition of this moment.
If we talk about the chance of pregnancy in a healthy woman of young reproductive age (20-26 years old), then in several medical sources you will find a figure of 22% per month. How was this percentage determined? How truthful is he? What is meant by this chance? In order to understand what kind of chance to get pregnant and have a baby in time is available to any healthy woman, let’s talk about how early pregnancy can be diagnosed. Of course, many of you are immediately mentioned pregnancy tests. Quite right, these tests can determine pregnancy, when implantation has already occurred, and the level of pregnancy hormone in urine has reached those indicators, when tests can “catch” this rise in hormone levels. But until this moment, is there no pregnancy? How can you still define it?
Let’s start with the well-known pregnancy hormone (and not only pregnancy) – progesterone. Where does a woman have progesterone? It is produced by the ovaries, especially the area where ovulation occurred. The follicle burst, the egg came out, and the volume of the bursting follicle quickly filled with blood (which on the ultrasound may look like bleeding in the ovary and what is shocking some doctors, and they send such a woman for an urgent operation), and while the egg travels through the fallopian tube, two the main cell types in the bursting follicle, which becomes the corpus luteum. Some cells begin to intensively produce progesterone so that, while the egg cell travels, the uterus has time to prepare for its adoption. Other cells produce female sex hormones (estrogens) and in very small quantities male sex hormones (androgens). And thanks to the increase in progesterone level, the endometrium of the uterus becomes “juicy”, loose, filled with a large number of substances important for the implantation of the ovum. Doctors call the introduction and attachment of the ovum egg implantation window. Outside this window, the attachment of the ovum is impossible! If this period is shortened under the influence of external and internal factors, or the staging of changes in the endometrium is disturbed, then the implantation can also be disturbed and result in miscarriage.
The peak level of progesterone in the blood is reached at about 5-7 days after ovulation, and this shows the amazing rationality of the female nature. Reaching the uterus at 4-6 days after ovulation and conception (this is the third week of pregnancy), the ovum (blastocyst) is in it from one to three days in “limbo”, that is, not yet attached to the wall of the uterus. It turns out that the pregnancy is already there, but, on the other hand, it is not there yet, because the fertilized egg can be removed by the uterus before its implantation, and the woman will not know about it. It is not as scary and terrible as some may seem. Inferior fetal eggs that cannot attach to the wall of the uterus are most often removed. During these 2-3 days of being in a “hanging state,” the fetal egg releases special substances that suppress the mother’s defenses because it is a foreign body for her body. Progesterone in turn suppresses the contractility of the uterus muscles, that is, it calms its response to a foreign body, relaxes the uterus, allowing the ovum to implant. Thus, the process of implantation begins, or the insertion-attachment of the ovum to one of the walls of the uterus. The growth of the progesterone level also leads to the fact that special formations appear in the endometrium – pinopods, which somewhat resemble tentacles (fingers). They appear between the 19th and 21st day of the menstrual cycle and exist only 2-3 days (with a 28-day cycle). Their appearance leads to the fact that the uterus is reduced in size, as it is compressed due to these protrusions inside, and the cavity itself also decreases in size, bringing the uterus wall closer to the fetal egg floating in it – nature reduces the distance between the uterus and the fetal egg for its successful attachments. Until the fertilized egg is attached to the uterus, the source of its nutrition becomes intrauterine fluid secreted by endometrial cells under the influence of high progesterone levels. It is important to understand that the maximum increase in progesterone is observed not on days 21-22 of the menstrual cycle, but on days 5-7 after ovulation. Got a difference? With a 28-day cycle, this will be the 21st day, and with cycles shorter or longer than 28 days, the peak of the increase in progesterone will fall on other days of the menstrual cycle. Those doctors who do not understand or do not know the specifics of fluctuations in hormone levels in women send their patients to donate blood to determine hormonal levels on certain days of the cycle, and if progesterone levels are lower than they expect to receive on the 21st day, immediately a diagnosis of progesterone deficiency is made and treatment is administered in the form of progesterone, which is extremely wrong and can have quite a few side effects for the entire female reproductive system. After all, progesterone suppresses ovulation! If you take it before ovulation, then do not expect pregnancy.