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Menstruation and the menstrual cycle: the most important basics explained simply

17 Jan, 2023

Menstruation and the menstrual cycle: the most important basics explained simply

The menstrual cycle and menstruation accompany women over several decades from adolescence to menopause. There is no doubt that monthly menstruation is an important part of every woman's life.

In the following, we will go into more detail about the basics of the menstrual cycle and menstruation. For example, we explain how long your period lasts on average, how much blood loss is normal and whether you can get pregnant during your period. We also discuss possible irregularities during your period.

The most important facts about periods and the menstrual cycle at a glance

  • The female cycle begins on the first day of menstruation and ends with the onset of the next period.
  • The menstrual cycle can last between 20 and 40 days and consists of four different phases.
  • The actual period usually lasts three to seven days and can vary in duration and intensity from woman to woman.
  • In principle, it is also possible to become pregnant during the period, as the sperm can survive in the female body for several days.
  • Although many women probably have a different impression, blood loss during menstruation is rarely more than 70 millilitres.
  • The colour of menstrual blood can provide important clues to health and should therefore be kept in mind.
  • Girls usually have their first period between the ages of 11 and 14, although upward and downward variations are not uncommon.
  • Between five weeks and a year can pass before the first menstruation after pregnancy.
  • Premature menstruation is mainly caused by hormonal fluctuations.

What is the menstrual cycle?period pants

The terms cycle and menstruation mean two different things. Menstruation, which is also called a rule, period or days, is the time when women have their period. A woman's cycle, on the other hand, is the entire period from the first day of menstruation until the onset of the next menstruation. 

How long is the menstrual cycle?

At some point in school you probably learned that the female cycle lasts a total of 28 days. However, this is far from the case for every woman. In fact, the length of the cycle can vary quite significantly from woman to woman. It is therefore perfectly normal for your cycle to last only 20 days or up to 40 days.

The phases of the cycle

The menstrual cycle can be divided into four different phases. The first phase is menstruation. The second phase is the follicular phase, which is followed by ovulation and the fertile days. The fourth and final phase of the cycle is called the luteal phase.


The cycle starts with day one of your period. The upper layer of the mucous membrane of the uterus, which was previously built up in case of pregnancy, detaches and is excreted from the body in the form of menstrual blood. As the muscles in the uterus contract and relax at irregular intervals, menstruation can sometimes be accompanied by unpleasant pain.

The follicular phase

Menstruation, which normally lasts up to seven days, is followed by the so-called follicular phase. During this phase of the cycle, the eggs, which are protected by a membrane, mature in the ovaries. Normally, at the end, only one of the eggs manages to migrate from the ovaries towards the uterus. At the same time, the mucous membrane in the uterus is built up in preparation for a possible pregnancy. If the egg is fertilised, it will nest in the uterus, where it will hopefully develop into a healthy baby over the next few months.

Ovulation and fertile days

The follicular phase is followed by ovulation. The protective shell of the egg bursts and the egg enters one of the fallopian tubes. It then travels down the fallopian tube to the uterus. Ovulation takes place two weeks before the start of the period. As mentioned above, the length of the cycle can vary from woman to woman, so it is not easy to determine the time of ovulation in advance. For example, if your cycle lasts 30 days, you ovulate on the 16th day. If your cycle lasts 36 days, you will ovulate on the 22nd day of your cycle. If you want to know exactly, we recommend tracking your cycle over a longer period of time with an appropriate app or a cycle calendar.

The luteal phase

After ovulation, it takes between four and six days for the egg to reach your uterus. During this time, the mucous membrane in the uterus continues to build up in anticipation of an impending pregnancy. If the egg was not fertilised on its way through the fallopian tube during the woman's fertile days, the hormone level drops. This is the signal for the uterine lining to be shed. Now your menstruation starts and the next cycle begins.

period underwearWhat can influence the cycle?

You probably know from your own experience that your menstrual cycle can sometimes be irregular and that menstruation can sometimes come earlier or later. Possible factors that can play a role in this context are stress, diet and general lifestyle. Apart from that, your cycle can also be affected by smoking or excessive alcohol consumption.

Duration of the period

On average, a woman's period lasts between three days and a week. If your period is very heavy, it can sometimes last a little longer. It is also not unusual for your period to stop for a short time and then start again.

If your menstrual bleeding is weak, your period will also be shorter. This is often the case, especially when you are on a strict diet or under excessive stress.

Because menstruation is something very individual, it can vary greatly from woman to woman in terms of its intensity and duration. Among the factors that play a role are genetics and age. Apart from that, diet also has an influence on a woman's period that should not be underestimated.

Nevertheless, you should keep an eye on the duration of your period. If your period is regularly shorter than three days or longer than a week, we recommend that you talk to your gynaecologist. After all, it is possible that there is an illness or a disturbance in your cycle.

Can you get pregnant during your period?

Many women wonder if it is possible to get pregnant when they are on their period. In principle, it is possible. Your period is not one of the most fertile days of your cycle. However, you should remember that the sperm can survive in your body for a few days and can therefore fertilise your egg without any problems at a later time. If you don't want to have children at the moment, you should use contraception during your period.

How much blood do you lose when you have your period?

Some women may think that they lose a lot of blood during their period. In fact, the amount is very small. Normally, you can expect to lose between 30 and 70 millilitres of blood during your period. If you lose more than 80 millilitres, your period is heavy.

Of course, it can happen for various reasons that a woman loses an excessive amount of blood during her period. If this is the case for you and you have to change your tampon every hour, you should contact your gynaecologist to find out the reasons for your heavy menstrual bleeding. 

Why you should keep an eye on the colour of your menstrual blood

Menstrual blood can vary in colour from pink to red to brown. For example, pink blood is usually a sign of low oestrogen levels, while dark red blood, which may even be lumpy, indicates high oestrogen levels. If the menstrual blood is light red, it is fresh blood. If it is brown, on the other hand, the menstrual blood is probably a little older. The brown colouring is caused by the oxidation of the blood associated with contact with oxygen.

In principle, certain changes in the colour of menstrual blood are nothing unusual and can also occur in the course of a single period. Nevertheless, the colour of your menstrual blood can give you important information about your health and can sometimes indicate the presence of diseases, such as infections or cervical cancer. It is therefore a good idea to keep an eye on it and talk to your gynaecologist if you notice anything unusual.

Your first period

At some point, every young woman will have her first period, which is also called menarche. Usually girls have their first period between the ages of eleven and fourteen. However, it is also possible for a woman to have her first period as early as nine or ten years old, or as late as 15 or even 17.

Like the period itself, the timing of the first menstruation varies from person to person. In order for it to start, the reproductive organs must be properly developed and sufficient sex hormones must be produced by the body.

From the first period onwards, women go through their menstrual cycle regularly. In the early days, however, it is not uncommon for periods to be quite irregular, and both the duration and the intensity of menstrual bleeding still vary quite a lot in young women.

What are the signs of the first period?

Not all girls have their first period at the same time. However, there are typical signs that announce it. One of these is the so-called white flow. This is a white to yellowish vaginal discharge that comes out in girls at the beginning of puberty and can be recognised by small spots in the panties.

White discharge indicates that the sexual organs have developed and the first follicles are forming in the ovaries. However, it is not possible to determine the exact time based on the white flow. However, the first period usually occurs about a year after it first appears.period knickers

Other signs that indicate that the first period is not too far off are, of course, the growth of pubic and underarm hair and breasts. The recently childlike shapes of the body are changing and becoming increasingly feminine.

The first period after pregnancy

When exactly the first period after pregnancy starts and how heavy it is varies greatly from person to person. In principle, menstruation can start again around five weeks after giving birth.cycle However, it is also quite possible for a whole year to pass after giving birth before the first period.

It is very common for women who are breastfeeding their babies to have a long delay before their first period, or even to have no period at all for a very long time. If you don't want to get pregnant again as soon as possible, you should still start using contraception again after six weeks. This is because ovulation cannot be ruled out from this point on, despite breastfeeding.

Periods every fortnight: Why is that?

As mentioned earlier, your menstrual cycle usually lasts between 20 and 40 days. However, it is not uncommon for menstruation to be premature and for women to get their period after only two weeks, for example. Premature menstruation is often caused by changes in hormone levels.

The following reasons, for example, are possible triggers for hormonal fluctuations:

  • Severe stress
  • Taking birth control pills 
  • Prolonged lack of sleep  
  • Rapid weight loss

Apart from this, the upcoming menopause is also associated with strong fluctuations in hormone levels in women.  

Even in this phase of life, when women actually expect their menstruation to stop soon, it can therefore happen that the period suddenly comes every fortnight instead of every four.

Is it really premature menstruation?

The supposed early menstruation is not always actually menstrual bleeding.   
In many cases, so-called spotting before the period is also responsible for the vaginal discharge. Spotting can occur during the fertile days or shortly before the actual menstruation and can often be recognised by its rather brownish colour.

Apart from this, unexpected bleeding can also occur a few days after sexual intercourse if this has led to fertilisation of the egg.

This is called implantation bleeding because the egg is implanting in the uterus. Usually, implantation bleeding is much weaker than a normal period. They also tend to be pinkish in colour. It should therefore not be difficult for you to distinguish them from possible premature menstruation.