How to define your cycle. Menstrual cycle: a general concept of its norm, regularity, failures and irregularities. The period of the menstrual cycle and its main phases. The degree of profusion and pain during menstruation. Why does your period cycle change every month?

09 November, 2012 13:46

What is this article about and how to use the information received?

This article contains answers to many questions that girls and women have about (menstruation).

Any woman should have information about the nature of the occurrence and the characteristics of the course of such an important physiological process. Our article will help you understand these concepts.

This information will be especially relevant for the following audience:

Young girls who have just started their period and know little about it;
Adult women who are concerned about the nature of their menstrual cycle, wanting to know how correctly everything is going on in their body;
Adult women of any age, if some changes have occurred in their menstrual cycle;
Adult women, in case of unusual occurrence;
Pregnant women, when menstruation occurs during pregnancy (at any time).

What is menstruation? Why and why is this happening?

Very often, women await in horror the onset of critical days, since for them this is a useless torment, unsettling for a week, and sometimes even longer. However, it is important to treat this as a normal physiological mechanism. After all, all the processes that occur in the female body before and after menstruation are nothing more than evidence of her reproductive function. That is, it is the woman in whose body a normal menstrual cycle occurs that is capable of carrying a child.

And now we will tell you why and why menstruation occurs, and what it should be in a healthy woman.

Thus, menstruation is a rejection of the mucous membranes of the female uterus, which were not useful for the development of pregnancy. This is the principle of the body of a healthy woman. But various diseases and certain conditions of a woman can disrupt the correct course of this process. They can disrupt the cycle and change the pattern of menstruation.

Severe pain as a symptom of the disease

It happens that the pain is so strong that it makes a woman completely unsuitable for normal life during this period. Severe pain often indicates a disorder and is called dysmenorrhea.

This diagnosis is confirmed if, along with pain, there are also signs such as:

Headache;
Dizziness;
Nausea;
Loss of consciousness;
Constipation or diarrhea.

The presence of such signs, unambiguously, serves as a reason for an immediate visit to a gynecologist. What this threatens, we will consider below.

Pain during menstruation. When should you see a doctor?

So, if you have severe pain during your period, you should seriously think about your health.

Pain can signal a number of conditions:

Myoma of the uterus;
Uterine cancer;
Polyps of the uterus.

In addition, you need to pay attention to the changes that have been happening to you lately.

So, if the following signs are present in you, you urgently need to contact your gynecologist:

Your periods are more painful than before;
Pain in the lower abdomen is very severe (you are constantly taking pain medications);
In addition to pain, the discharge itself has become more abundant (one pad is enough for you for less than 2 hours);
Along with pain, other disorders occur (weight loss, cycle disruption, inability to become pregnant).

How to relieve pain?

As we said, it is normal to have some pain during your period.

Therefore, to relieve your condition, you can use some common techniques:

Get enough sleep these days. But just lying all day is not an option. On the other hand, being motionless worsens the condition;
Transfer difficult mental and physical activities until the period ends;
These days you need to move more, walk, play sports. You only need to exclude heavy physical activity. The ideal option would be either Pilates;
Sex allows relieving pain and (thus, muscle tension of the uterus decreases);
If the pain is severe, you can take an anesthetic (, analgin, naproxen). It must be remembered that girls under 16 years old should not take aspirin (acetylsalicylic acid).

If menstrual pain is constant, every month, and if your doctor does not see any abnormalities in health, he can prescribe preventive medications. They will help reduce pain during critical days.

The period of the menstrual cycle. How regular should it be?

Ideally, a healthy woman will have regular periods, and there is a certain period of her cycle. But insignificant deviations from the average cycle time are not always the result of any health disorder. The fluctuation of the beginning of menstruation, earlier or later, by several days (approximately 3 - 5 days) is insignificant.

Particular attention needs to be paid to understand that a regular menstrual cycle is not the fact that menstruation occurs on a certain day. Every month, on the same day, menstruation should not begin. The regularity of the cycle lies in the observance of the period of the break itself between the previous and next menstruation. This is influenced by the number of calendar days in a month, the onset of a leap year and the time of day when the previous months came.

Let's give an example. A woman has a normal menstrual cycle of 27 days. Last month my period started on March 1st. Thus, the beginning of the critical days of the next month should fall on the date of March 27th (but not April 1st). But next month it will be April 23rd. Etc.

Stable cycle violations and failure. What can delay menstruation mean?

If the irregularities in the cycle are insignificant, or they are of a single nature, there is no cause for concern. But here are frequent and long-term and, as well as its irregular nature, may indicate many gynecological diseases. The unpredictable onset of menstruation, frequent delays should be the reason for immediate medical attention.

If a delay occurred in a woman whose cycle was previously stable, this may indicate the following changes:

Pregnancy;
The result of exposure to certain factors (, nervous strain,);
Disease.

The normal state of a woman after menstruation

After the end of bloody discharge, a woman may notice some symptoms.

Several days after menstruation, the following signs may persist:

Mild pain in the lower back, lower abdomen and side;
Mild headache, nipple tightness, slight tingling in the chest;
Slight when pressed;
Weak spotting (daub). Their color can be brown, pink, yellow or transparent.

If, at the end of menstruation, pronounced pains are felt in the abdomen or lower back, you should immediately see a gynecologist. If the discharge described above does not go away on the 3rd - 4th day after the end of menstruation, this may also be a signal of illness. Especially if, along with this, other symptoms appeared (fever,

Menstrual cycle - This is a series of changes that occur in the genitals of a woman at approximately the same time intervals, aimed at the possibility of conception. This is a natural part of any woman's life, representing a well-established cycle of ovulation and menstruation, the average duration of which is 28 days. A woman's health is directly related to the concept of the menstrual cycle.

To know which the menstrual cycle is normalhow long menstruation lasts, you should know the structure of your body and genitals in particular.

Anatomy of the female genital organs.

A woman's sex organs consist of external and internal. The external genitals are responsible for sexual sensations and take part in sexual intercourse, while the internal ones ensure conception.

The external genitals of a woman consist of the labia majora and labia majora, the pubis, and the clitoris. The labia minora limits the urethra and the vestibule of the vagina. The clitoris is the point of their connection. It is a unique organ, covered with a thin mucous membrane, responsible for the concentration and accumulation of sexual sensations.

The internal female genital organs include: the vagina, ovaries, fallopian tubes, cervix, uterus. The vagina is connected to the cervix, which in turn expands. An egg enters the uterus, and if a pregnancy occurs, an embryo and an intrauterine fetus develop in it.

The menstrual cycle and its periods.

Every menstrual cycleprovides for the preparation of the female body for a possible pregnancy. Its duration is on average 28 days, but small deviations up or down are the norm.

All processes in the female body are divided into several phases:

The menstrual phase is the period of bloody discharge from the uterine cavity. Through the genitals with menstrual blood, cells are removed from the uterus, to which, in case of possible fertilization, the egg should have attached itself. This period lasts from 3 to 6 days.

Follicular phase - begins simultaneously with the menstrual phase and lasts 14 days. In the process of enhanced synthesis of certain hormones in the ovaries, a follicle grows, in which a new egg cell develops. This phase is also characterized by an intensive renewal of the endometrium of the uterus, preparing it for the adoption of an egg.

The ovulatory phase lasts about three days. In the process of hormonal exposure, a mature and ready-to-fertilization egg is released from the follicle. Further, it moves through the lumen of the fallopian tube into the uterine cavity and waits for possible fertilization. The egg cell lives for no more than two days, the process of preparing the endometrium continues in the uterus.

Luteinizing phase - final period of the menstrual cycle and lasts 11-16 days. There is an active synthesis of the hormones estrogen and progesterone. Their function is to prepare a woman's body for pregnancy. Due to the natural change in hormonal levels, at this stage, women often have premenstrual syndrome. These are well-known symptoms such as pain in the lower abdomen, increased appetite, mood swings, enlargement and tenderness of the mammary glands.

Critical days.

What changes occur in a woman's body during menstruation?

Day 1. On the first day of your period there is a rejection of the cells covering the walls of the uterus, to which the fertilized egg was supposed to attach. Since fertilization did not occur, the old endometrium, together with bloody secretions, is excreted through the genitals. Many women feel very uncomfortable during this period. Unpleasant sensations can be associated with uterine contraction and are the norm.

Day 2. The second day of the menstrual cyclemay also be accompanied by heaviness and soreness in the lower abdomen. At this moment, a new egg cell is formed in the woman's body.

Day 3. The third day of the menstrual cycle characterized by the presence of a wound surface on the walls of the uterus. This occurs as a result of the rejection of the old endometrial cover. During this period, it is recommended to exclude sexual intercourse, since the likelihood of infection is very high.

Day 4. On the fourth day of the cycle unpleasant symptoms stop, but you still need to take care of yourself. You should be less tired, you only need to perform feasible physical activity. These limits will help reduce the amount of blood loss over the entire period.

Day 5. Average duration of menstruation is five days. Since the body of each woman is individual, discrepancies are possible. On the last day of menstruation, the healing process of the walls of the uterus is completed. The woman's health becomes much better, all unpleasant sensations disappear.

Profuse bleeding during the menstrual cycle.

During menstruation, bleeding can be intense, or it can be scanty. Factors affecting the intensity of discharge may be different. Influence on the duration of the menstrual phase and the abundance of blood loss can have: diet, stress, contraceptives used, etc. There are established average standards regarding the duration of menstruation and the intensity of bloody discharge. But these indicators may be different for different women, as well as they may differ for the same woman in different menstrual cycles, which is within the norm.

Depending on the abundance of menstrual flow, you should choose the right hygiene products, in particular tampons. They differ in varying degrees of absorbency. You can choose the right tampons yourself, but it is better to entrust this to your doctor. If the hygiene product is chosen correctly, this will ensure good health and a minimum of inconvenience during menstruation.

Woman's behavior and hygiene during the menstrual cycle.

Every woman experiences her period in her own way. Someone feels the same as before these days, and someone does not get out of bed and uses pain relievers. Even critical days do not affect the well-being and performance of a woman, you should still slightly change the rules of behavior. This will help to cope with profuse blood loss, pain, nausea, and general fatigue.

During menstruation, a woman should avoid all kinds of stressful situations. Emotional overexcitement provokes an abundance of secretions and a deterioration in well-being. It is important during this period to concentrate your actions on pleasant moments. This is chatting with friends, watching a good movie, a favorite treat.

Relaxation and actions that increase blood circulation will contribute to the reduction of pain syndrome. Lying in a warm bath or with a heating pad on your stomach will have a positive effect on your overall well-being.

Drinking plenty of fluids can help manage premenstrual syndrome. Water can help avoid fluid retention and bloating.

The diet should contain more vegetables, fruits, fresh juices. It is useful to include in food more magnesium and vitamin E. The use of spicy, salty, coffee, tea should be limited.

During menstruation, you need to take care of your body hygiene. On these days, you should take a shower more often than usual, while the water should not be hot, but warm. Tampons and pads need to be changed frequently, otherwise pathogenic bacteria may proliferate.

Knowledge of the features of the flow of the main stages of the menstrual cycle, the anatomy of your body, the rules of behavior on critical days will help to avoid problems with your health and well-being.

The nature of menstruation and their regularity are important indicators of women's reproductive health. The body is sensitive to any stress, so there may be occasional deviations from the norm, which are not considered a pathology. However, if the violations are persistent, this may indicate a disease. It is convenient to mark the days of the beginning and end of menstruation in the calendar. This will allow you to find out the duration of the next cycle and not miss unusual changes. It is important to understand what processes occur between periods, when conception is possible, why critical days come more or less often than usual.

Content:

What is the cycle duration for?

The processes in the female reproductive organs are repeated every month, on average after 28 days. Due to the individual characteristics of the organism, the cycle can be shorter (up to 21 days) or lengthened (up to 35 days). The main indicator of health is not so much the number of days in it, as the constancy of this indicator. If a woman has her period regularly after 5 weeks or after 3 weeks, this is normal. But if they come after 35-40 days, then after 20-21, and this happens repeatedly, this is already a pathology.

Prepare for the onset of menstruation, take measures to alleviate premenstrual syndrome (plan, for example, the load during critical days).
Provide for the possibility of pregnancy in the middle of the cycle, increase attention to contraception.
Consider which days will be most favorable for conception and the onset of the planned pregnancy.
Notice the onset of pregnancy and roughly calculate the day of birth.
Plan a preventive visit to specialist doctors (gynecologist, mammologist).

Noticing persistent irregularities in the frequency of the onset of menstruation, it is necessary to consult a doctor in time to prevent early menopause or the occurrence of diseases of the uterus and ovaries.

What processes occur during the cycle of menstruation

The processes taking place in the female reproductive system are directly related to the ratio of sex hormones that are produced in the ovaries. The cycle is conventionally divided into phases: follicular, in which the ovum matures, ovulatory and luteal - the phase of the onset and maintenance of pregnancy.

Follicular phase

The beginning is considered the first day of menstruation. Its duration in different women ranges from 7 to 22 days (the duration of this particular phase depends on whether a woman's cycle is short or long). The phase begins with menstruation - cleansing the uterus from the layer of the endometrium formed earlier. Menstruation occurs when the fertilization of the egg does not occur.

By the end of menstruation, a follicle-stimulating hormone begins to be produced in the pituitary gland, under the influence of which several follicles (vesicles with eggs) develop in the ovaries. One of them stands out, the largest (dominant), which grows to about 20 mm in diameter. The growth of the rest stops.

In the process of follicular development, estrogens are released, due to which a new layer of the mucous membrane (endometrium) begins to grow in the uterus.

Ovulation

The follicle that has matured together with the egg cell (the so-called graaf bubble) bursts at 7-22 (on average 14) days of the cycle. In this case, the hormone lutein is released from the pituitary gland, which contributes to the formation of the corpus luteum from the ruptured membrane. Its purpose is to produce progesterone, which prevents the development of new follicles. Ovulation and progesterone production usually last for 16-48 hours.

Luteal phase

It is called the corpus luteum phase. This temporary gland functions for about 12 days to produce progesterone. If the fertilization of the egg occurs, then the corpus luteum continues to function until the placenta is formed in the endometrium. If pregnancy does not occur, then the gland dies off, menstruation begins.

Conception is most likely during the few days when ovulation occurs and a mature egg is released. Carefully observing the changes in the body for half a year, a woman can roughly predict when the "dangerous" days will come. The total duration of the luteal phase is 13-14 days and is practically unchanged.

Video: How to calculate the duration of menstruation, determine ovulation. Cycle phases

Causes of menstrual irregularities

In addition to fluctuations in the timing of the onset of menstruation, menstrual irregularities also include the duration of menstruation less than 3 or more than 7 days, a change in the intensity of blood flow (less than 40 ml or more than 80 ml for all days), and the absence of ovulation.

The reasons for violations can be:

Diseases of the reproductive and endocrine organs. You need to know how to count the menstrual cycle so as not to miss the onset of the disease.
Hormonal changes in the course of natural age-related changes (maturation, menopause). In puberty, the maturation of the ovaries is just beginning, therefore, in the first 2 years, girls' periods may be delayed by 2-6 months. Often, the maturation of the ovaries is completed only during the first pregnancy. For many women, the cycle stabilizes after giving birth.
Physiological processes during the recovery period of the body after pregnancy and childbirth, during lactation.
Hormonal disorders after abortion.
An imbalance in hormones caused by stress, medication, weight loss or weight gain.

The older a woman is, the more likely it is that violations will occur, since possible causes accumulate (the number of births, abortions, the consequences of gynecological and other diseases), the body ages.

Why the cycle is lengthening

The reason for the increase in the duration of the cycle may be the lack of ovulation due to the defective development of the follicles. In this case, the corpus luteum is not formed and the level of progesterone does not increase. In such conditions, under the influence of estrogens, the growth of the endometrium continues until it begins to break down mechanically. In this case, the onset of menstruation is significantly delayed.

Another reason for the lengthening of the cycle may be the too long existence of the corpus luteum after pregnancy has not occurred. This anomaly is determined using ultrasound.

Addition: The opposite situation is also possible. A woman has a delay in her period due to the onset of pregnancy, but when she comes to the gynecologist for a checkup, it turns out that there is no corpus luteum in the ovaries, although it should be there and provide nutrition for the embryo. This speaks of the threat of miscarriage. Requires special treatment with hormones.

Reasons for a shortened cycle

The cycle is shortened due to the fact that the corpus luteum dies off earlier than usual, or the maturation of the follicle and ovulation occur faster.

Often, deviations in the duration of the cycle are the body's response to the emergence of extreme living conditions, when, for health reasons or due to a difficult life situation, bearing healthy offspring is impossible. For example, during the war, women had their periods altogether.

Video: The duration of the menstrual cycle. Reasons for deviations

How cycle times are calculated

The countdown starts from the first day of your period. And it ends on the last day before the next menstruation. How to correctly calculate the cycle of menstruation, taking into account the different number of days in each month, can be seen in examples.

Example 1. The woman had her previous period on March 5, and the next one came on April 2. The duration of the cycle is 27 (number of days from 5 to 31 March) + 1 day (1 April) \u003d 28 days.

Example 2. The previous period was September 16, the next one was October 14. The cycle time is: 15 (September 16-30) + 13 (October) \u003d 28 days.

Example 3. The previous period was on February 10 (a leap year), and the next came on March 6. The cycle is: 20 (from February 10 to February 29) + 5 (in March) \u003d 25 days.

Single deviations should not cause alarms, they can be considered the norm. But with long-term violations, it is necessary to undergo an examination to find out the cause.

What is the menstrual cycle? First of all, you can ask your gynecologist about this. It is difficult to say something new about the process that every woman goes through every month. Moreover, any of them have their own experience of experiencing such a state. Very often this topic begins in women's conversations. Usually, the discussion smoothly turns to first aid for especially painful menstruation, which for a long time can knock a woman out of her usual rut of life. Just 15 minutes of discussion - and you will receive hundreds of recipes on how to help yourself, your beloved, in such a difficult time for the female body. Today we'll talk about how to correctly calculate the menstrual cycle and how it starts.

For the first time, girls have to learn about what menstruation is, on average, at 12 years old. But, as you know, this figure is increasingly shifting towards a younger age. Now, having learned that the girl's first period began at the age of 9, no one will be surprised. But in general, the time of onset of changes in the child's body depends on race, lifestyle, amount of physical activity and hereditary characteristics.

The first signs of approaching puberty - the rapid growth of the girl's body begins, she has a clearly visible chest.

In older women, the opposite process begins. After the depletion of the follicles in the ovaries, menstruation completely stops. Between these two events of the beginning and the end, there is a rich, active life, accompanied by peaks of hormonal activity. A woman's life will now be measured not only by months, years, but also by menstrual cycles.

What is the menstrual cycle? This is a time period that lasts from one period to another and includes 2 periods. The first is when the maturation and release of the egg occurs. And the second, when the uterus creates conditions favorable for the implantation of an already fertilized cell. If you calculate the menstrual cycle, then on average the whole process takes about 28 days. This figure depends entirely on the individual characteristics of the organism. The first day that menstrual blood appears is considered the first day of the menstrual cycle. On average, up to 80 ml of blood is lost in one period. A discharge exceeding this figure in volume is a deviation from the norm and requires a visit to a doctor. Your period usually lasts 4 to 6 days.

The main volume of blood loss occurs on days 1 and 2. It is important to know which day is the start of the cycle. In general, it is very important to record the beginning of the menstrual cycle. First of all, so that the malaise and the accompanying condition are not taken by surprise.

A normal cycle is an important indicator of women's health. The ability to count your periods can help determine the most favorable moment for conceiving a child.

How to count the cycle of menstruation correctly? It is also important to do this in order to timely identify the presence of diseases, one of the signs of which is the lengthening or shortening of the menstrual cycle. In order to correctly calculate the menstrual cycle and understand a certain rhythm of changing one to the other, it is necessary to record the beginning of the first day of menstruation and the first day of the next for several months. As a result, we will get a summary table, according to which the days of the beginning and end of the menstrual calendar will be clearly visible. This table will help to calculate the cycle of menstruation, to identify its lengthening when the distance between the first day of the previous menstruation and the first day of the next exceeds 35 days. When does the lengthening or shortening of the menstruation occur? Elongation - when it lasts more than 7 days. The shortening is less than two days.

Menses can be profuse and scarce. In any case, with profuse, painful menstruation, accompanied by spastic pain or a feeling of heaviness in the lower abdomen, or in the complete absence of critical days, it is necessary to urgently consult a gynecologist. Spotting or bleeding may be another warning sign. All these deviations from the norm can serve as signs of serious illness. In order to identify all these violations, a table or calendar should be kept. Menstrual dysfunction can be caused by bad habits, in particular smoking.

Sometimes bleeding may begin between critical days. This could be a sign of a tumor in the body or cervix.

How to count the menstrual cycle correctly? Any girl or woman can do this, because the process is quite simple. Unfortunately, at present, not all women know how to count the cycle of menstruation, and if they do, they do not do it regularly. Meanwhile, the algorithm is easy to understand. It is enough to take a simple example and based on it, calculate the duration of your period.

Calculation of the cycle of menstruation

How to determine the menstrual cycle by calculating the days of the onset of menstruation? Let's consider an example:

Let's say the critical days began on March 3. So this is the first day of the menstrual cycle.
If calculated correctly, the next monthly bleeding in a normal cycle should begin on April 4.
This day will be considered the first day of the next period.
And April 3 will be the last day of the previous cycle, which will be 28 days.

As you can see, there is nothing difficult in counting. How to calculate your period using a simple example quickly becomes clear.

Every woman should take care of her health, including the normal functioning of the reproductive system.

This is especially true of control over the cycle of menstruation. Many gynecological diseases are asymptomatic, and it is very difficult to identify them in the initial stages. Only due to disturbances from menstruation can an assumption be made about the presence of one or another ailment. Therefore, the question of how to calculate the duration of critical days is very relevant.

By definition, the menstrual cycle is menstruation

estrogen and progesterone
Follicular phase.

Ovular phase

menopause

Luteal phase

pregnancy test

What does the menstrual cycle mean and what is it? What is the physiological basis and significance of the menstrual cycle and menstruation.

Menstruation is a cyclical rejection of the lining of the uterus (endometrium), accompanied by bleeding from the vagina. Menstruation occurs periodically, about once a month, throughout the entire reproductive period of a woman's life. Menstruation begins in adolescence and disappears completely with the onset of menopause. The main point of menstruation and the menstrual cycle is to prepare a woman's body for conceiving a child.

What are menstruation and menstrual cycle?

By definition, the menstrual cycle is the period from one period to the next. The first day of your period (bleeding from the vagina) is considered the first day of that menstrual cycle. The last day before the next menstrual period is considered the last day of that menstrual cycle.
For example, if your period begins on January 3, then that day is considered the first day of that menstrual cycle. If the next menstrual period occurs on February 2, then February 1 will be the last day (it turns out to be the 28th day) of that menstrual cycle, and February 2 will be the first day of the next menstrual cycle.
Typically, the duration of the menstrual cycle ranges from 25 to 36 days. Although usually, in the examples, a cycle with a duration of 28 days is most often taken, only 10-15% of women have such a cycle.
The duration of the first menstrual cycles (menarche), as well as the last cycles (during the onset of menopause) can vary quite a lot, which is explained by hormonal changes that take place in a woman's body during these periods.
Menstrual bleeding (menstruation itself, menstruation, "red days") usually lasts from 3 to 7 days, and on average lasts about 5 days. Blood loss during one menstrual cycle is usually 15 to 75 ml.

How is the menstrual cycle regulated? Why and why do such cyclical changes occur in a woman's body?
The whole point of the menstrual cycle is to prepare a woman's body for a possible pregnancy. Unlike many animals in which the possibility of conception appears only once a year or once every several years, a person has the opportunity to conceive a child almost every month. Every month, cyclical changes occur in the body of a woman of reproductive age, preparing her entire body (and mainly the genitals) for a possible pregnancy. These cyclical changes are called the menstrual cycle.
The central event (in terms of importance and time) of each menstrual cycle in a healthy woman is ovulation - the release of an egg that can be fertilized by a sperm and give rise to a new life. The first half of the menstrual cycle is about growing a mature egg and preparing a place in the uterus for development if it is fertilized. In the case when the egg is fertilized, the development of the menstrual cycle stops and it goes into pregnancy. If fertilization does not occur, the egg dies, and all changes in the woman's body undergo reverse development during the second half of the menstrual cycle, until the start of the next cycle. Each menstrual cycle begins with menstruation - which is the "cleansing" of the uterine cavity, which prepares to receive a fertilized egg in the middle of the cycle.
The menstrual cycle is regulated by hormones. Two hormones play a major role in the development of the menstrual cycle: luteinizing hormone (LH) and follicle stimulating hormone (FSH). Both of these hormones are secreted by the pituitary gland (a small gland adjacent to the lower part of the brain). Luteinizing hormones and follicle-stimulating hormones provoke ovulation and "force" the ovaries to produce the female sex hormones estrogen and progesterone. Estrogen and progesterone, in turn, "force" the uterus and mammary glands to prepare for possible fertilization and pregnancy. The menstrual cycle has three phases: follicular (before the egg is released), ovular (when the egg is released), and luteal (after the egg is released).
Follicular phase.
This phase begins on the first day of menstrual bleeding (day 1 of the menstrual cycle). The main events of this phase are

development of 1 follicle in the ovaries and cleansing of the uterine cavity after the previous cycle.
cleansing the uterine cavity after the previous cycle

At the beginning of the follicular phase (immediately after the end of the previous cycle), the lining of the uterus (endometrium) is filled with nutrients and blood vessels necessary for the growth of the embryo during the first period of pregnancy. The viability and growth of the uterine mucosa directly depend on the concentration of female sex hormones in the woman's blood. If, after ovulation, which took place in the middle of the cycle, pregnancy did not occur, the concentration of estrogen and progesterone in the blood decreases to a critical level (during the last phase of the previous cycle), and the first day of the new cycle begins rejection of the thick mucous membrane of the uterus, which in turn manifested by bloody discharge from the vagina (menstruation, menstruation).
At the same time, the woman's pituitary gland increases the production of FSH (a hormone that stimulates the growth of follicles). This hormone stimulates the growth of the follicle in the ovaries. A follicle is a small cavity inside the ovary in which 1 egg grows (from which an embryo can develop if fertilized). In healthy women, the concentration of FSH and the size of the follicle increase proportionally during the first phase of the menstrual cycle and reach a maximum after 13-14 days from the first day of menstruation. During the follicular phase, the cells of the follicle surrounding the egg produce large amounts of estrogen, which stimulates the development of the lining of the uterus and vagina.
On average, the entire follicular phase lasts approximately 13-14 days. Of all the three phases of the menstrual cycle, the duration of this phase varies the most. Closer to menopause, the follicular phase becomes shorter.
Despite the fact that at the end of the follicular phase, the size of the follicle and the eggs in it become maximum, it still remains closed inside the ovary, in a place inaccessible to spermatozoa. In order for the fertilization of the egg to occur, the follicle (membrane) must burst and release the egg. Follicle rupture (ovulation) occurs under the action of luteinizing hormone.

Ovular phase
The ovular phase (ovulation) begins with a sharp increase in the level of luteinizing hormone in the blood. Luteinizing hormone stimulates the growth of the follicle and the release of the egg.
The ovular phase usually lasts from 16 to 32 hours. The end of this phase is considered to be the release of the egg.
At the time of ovulation, some women may experience short-term pain in the lower abdomen.
Within 12 to 24 hours after the release of the egg, a sharp increase in the level of luteinizing hormone in the body can be determined using a special urine test. This analysis can be used to identify the fertile period (the period when the probability of pregnancy is highest). The egg can be fertilized no later than 12 hours after its release. Fertilization of an egg is more likely if there is sperm in the woman's reproductive organs before the release of the egg, that is, in the case when intercourse occurred several hours before or after ovulation.
Ovulation is the centerpiece of every menstrual cycle. Despite this, in a number of cases (for some diseases, against the background of taking hormonal contraceptives, after childbirth, during the onset of menopause), anovulatory cycles often occur, that is, cycles during which ovulation and the release of a mature egg do not occur.

Luteal phase
This phase begins immediately after ovulation, lasts about 14 days and ends just before the start of the next menstrual period or progresses into pregnancy.
A woman's body "learns" about the presence or absence of pregnancy only 10-13 days after ovulation, and all this time "diligently prepares" to receive an egg, which may have been fertilized.
In the luteal phase, the ruptured follicle closes and forms the so-called corpus luteum - an accumulation of cells that produce progesterone. The role of the corpus luteum is to prepare the uterus for a possible pregnancy.
The progesterone produced by the corpus luteum causes the endometrium (the inner lining of the uterus) to thicken and fill with fluid and nutrients necessary for the unborn baby. Also, during the luteal phase, progesterone causes a slight increase in body temperature (basal temperature) and maintains that elevated temperature until the onset of menstruation. Due to the fact that the corpus luteum develops only from a burst follicle and produces progesterone, which contributes to an increase in temperature, only when ovulation has occurred, an increase in basal body temperature is used to determine whether ovulation has occurred or not.
Increases in blood progesterone and estrogen levels during the first and third phases of the cycle increase the flow of the mammary glands, which can cause the breasts to swell slightly and become more sensitive (especially in the last days of the menstrual cycle, before the onset of menstruation).
If the fertilization of the egg does not occur, the corpus luteum disappears after 14 days, and the level of progesterone and estrogen in the woman's blood drops to a critical level. From this point on, a new menstrual cycle begins.
If the egg has been fertilized, the luteal phase goes into pregnancy, and menstruation does not occur. This happens as follows: if the egg has been fertilized and successfully attached to the uterus, the cells around the developing embryo begin to produce a special hormone - human chorionic gonadotropin. This hormone maintains the life of the corpus luteum, preventing its disappearance.
The corpus luteum, in turn, continues to produce progesterone until the placenta of the unborn child is formed. Human chorionic gonadotropin (hCG) is used to determine pregnancy with a home or laboratory pregnancy test. This test measures the concentration of this hormone in the urine.

As it became clear from the above material, the menstrual cycle is a complex process of global cyclic rearrangements in a woman's body, the purpose of which is to create favorable conditions for the development of pregnancy.