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General Practice 2023

Menstrual cycle: what é, phases, how to count and how long it lasts

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Menstrual cycle: what é, phases, how to count and how long it lasts
Menstrual cycle: what é, phases, how to count and how long it lasts

The menstrual cycle lasts an average of 28 days and corresponds to the time interval between the first day of menstruation and the last day before the next menstruation.

The menstrual cycle is divided into 3 phases, according to the hormonal changes that occur in a woman's body. Menstruation represents the fertile years of a woman's life, which begin in adolescence and last until menopause.

It is normal for the duration of the cycle to vary between 21 and 35 days, but cycles with shorter or longer intervals can be a sign of a he alth problem, such as polycystic ovary syndrome and, therefore, should be evaluated by a gynecologist.

Menstrual Cycle Calculator

To find out when your next period will be, fill in the data in the calculator:

If you want to know when your most fertile period is, please use the fertile period calculator.

Phases of the menstrual cycle

The normal menstrual cycle lasts an average of 28 days, starting on the first day of menstruation and ending when the next month's menstruation begins.

Each menstrual cycle is divided into 3 phases:

1. Follicular Phase

This is the first phase of the cycle, which starts on the first day of menstruation and lasts between 5 and 12 days. At this stage, the brain increases the production of follicle-stimulating hormone (FSH), which leads the ovaries to mature their eggs.

With this maturation, the ovary also begins to release greater amounts of estrogen, which is another hormone, responsible for making the lining of the uterus ready for a possible pregnancy.

2. Ovulatory phase

In this phase, estrogen levels continue to increase and lead the body to produce luteinizing hormone (LH), which is responsible for selecting the most mature egg and making it leave the ovary, which is when ovulation occurs., usually around day 14 of the cycle.

After being released, the egg travels through the tubes until it reaches the uterus. Normally, the egg survives for 24 hours outside the ovary, so if it comes into contact with sperm, it can be fertilized. Since sperm can last up to 5 days inside a woman's body, it is possible that if a woman had unprotected intercourse up to 5 days before ovulation, she could become pregnant.

3. Luteal Phase

This phase takes place, on average, in the last 12 days of the cycle and, during these days, the follicle, left by the egg inside the ovary, begins to produce more progesterone, to continue preparing the uterine lining for the case of a possible pregnancy.In addition, there is also an increase in estrogen production, which is why some women may experience breast tenderness, mood swings, and even swelling.

When fertilization does not take place, the follicle shrinks inside the ovary and, therefore, estrogen and progesterone levels decrease until the lining of the uterus is shed, starting menstruation and the next menstrual cycle.

If there is fertilization, the egg is stuck to the walls of the uterus and the body begins to produce hCG, a hormone that keeps the follicle producing estrogen and progesterone at high levels to maintain the lining of the uterus until the formation of the placenta.

How to count the cycle

To count how many days the menstrual cycle lasts, consider the time interval between the first day of menstruation, until the day before the next menstruation.

For example, a woman who menstruated on day 5 should consider the first day of menstruation as day 5. If the next menstruation occurs on day 30, she should consider the end of the cycle on day 29. In this case, the menstrual cycle is 25 days (including day 5 and 29).

This type of calculation works best for women who have a regular menstrual cycle. Those who have an irregular cycle should average the number of days in each cycle in a given period of time. For example, for 3 or 6 months, note the duration of each cycle and, at the end, add the total number of days and divide by the number of cycles you had. See also how to calculate the fertile period in an irregular cycle.

How long does it last

The length of time the menstrual cycle lasts varies from woman to woman, with an average of 28 days being considered normal, which means that every 28 days a woman menstruates. However, the duration of the menstrual cycle can vary between 21 to 35 days.

Menstrual cycle duration shorter than 21 days or longer than 35 days should always be evaluated by the gynecologist, to check for any changes or he alth conditions that may be influencing the cycle, such as polycystic ovary syndrome, uterine fibroids or ovarian failure, for example.

Signs of fertile period

The signs that indicate that the woman is in the fertile period are mainly: transparent discharge similar to the egg white; increased breast tenderness and mild pain in the uterus region, similar to mild colic.

In addition to these signs, it is also possible to identify ovulation through the ovulation pharmacy test. Here's how to use the ovulation test.

Irregular menstrual cycle

Irregular menstrual cycle is one in which it is not known when menstruation will come. The most common causes of irregular cycle are:

  • Beginning of fertile life in adolescence, up to 2 years after the first menstruation;
  • Post pregnancy period;
  • Pre-menopause, due to intense hormonal changes;
  • Eating disorders that cause excessive weight loss, such as anorexia nervosa;
  • Excessive physical activity, especially in female athletes;
  • Hyperthyroidism;
  • Polycystic Ovaries;
  • Change of contraceptive;
  • Stress or emotional disturbances;
  • Presence of inflammation, polyps or tumors in the female reproductive system.

In the presence of an irregular menstrual cycle or when the menstrual cycle has not occurred for more than 3 months, a gynecologist should be consulted to investigate the cause of the problem. See 10 Myths and Truths About Menstruation.

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