Menstrual cycle: everything you need to know about the female cycle

Whether it's to find out when your next periods will fall, to conceive a baby, or simply to understand yourself better, knowing how the menstrual cycle works is very interesting. So, we're giving you everything you need to know in this article.


What is the menstrual cycle?

From puberty, to the onset of menarche periods and until menopause, women have a menstrual cycle lasting around 35 years. A woman's fertility takes the form of a cycle, divided into 4 phases. During these 4 phases, there are hormonal fluctuations, which have an impact on many aspects of a woman's life.

The menstrual cycle lasts about 28 days, but the length varies from person to person: some have a very short cycle of 21 days, while others have much longer cycles of 30 days or more.

What are the hormones of the menstrual cycle?

As explained above, hormones and their fluctuations direct the different phases of the menstrual cycle.

Oestrogen and progesterone: the best-known ones

Estrogens and progesterones are the main and most important hormones in the menstrual cycle. Estrogens have a regulatory role. They are hormones produced by the follicles (located in the ovaries) and make the endometrium (the lining of the uterus) thicker and therefore ready to receive a fertilized egg. Just before ovulation, estrogen levels rise.

Progesterone is the second sex hormone. It is produced when the ovum has already been released, by the so-called "corpus luteum" (the remains of the follicle). This hormone is very useful in preserving the endometrium and allowing the implantation of a fertilized egg. Progesterone peaks on the 21st day of the menstrual cycle, one week after ovulation.

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Follicle-stimulating hormone (FSH) is not secreted by the ovum, but by the pituitary gland in the brain. What does it do? To bring the follicles in the ovary to maturity. This hormone also plays a role at the onset of puberty.

Levels of this hormone rise during menstruation, falling just before ovulation.

Luteinizing hormone (LH) is also a hormone produced in the brain. Its mission? That ovulation occurs, releasing the egg ready for fertilization. 

What are the phases of the menstrual cycle?

The menstrual cycle is made up of different phases, each with its own particularity:

1. Follicular phase

The first begins with the first day of menstruation, corresponding to the first day of the cycle and the follicular phase. It generally ends on day 14, with ovulation or the ovulatory period. The ovaries are in fact preparing to release an egg. FSH is secreted by the pituitary gland, causing the follicles, which produce estrogen, to swell.

At the end of follicle growth, with the peak of the luteinizing hormone, an oocyte is released. Together with the sperm, the oocyte forms the first cells of the embryo during fertilization.

The endometrium will thicken in preparation for the fertilized egg. During this phase, you may feel :

  • migraines 
  • increased libido
  • fuller breasts

2. Ovulation

The third phase isovulation. This generally occurs on the 14th day of the cycle. Once released, the ovum takes 24 hours to reach the fallopian tubes, and survives for between 24 and 48 hours. For pregnancy to occur, the ovum must be fertilized within this timeframe.

Several signs may appear during this phase: 

  • an increase in your body temperature: to make the ground more favorable to spermatozoa and their survival, the temperature generally rises by 0.5 degrees.
  • During this period, the cervix is also more open, making discharge whiter.

3. Luteal phase

Finally, once the egg has been released, the luteal phase begins. During the luteal phase, progesterone levels rise to help the uterus mature. Then, at around 21 days, progesterone production begins to decline. When estrogen and progesterone levels reach a very low level, bleeding will start to occur, leading to bleeding (and therefore periods).

During the luteal phase, you may experience various symptoms:

  • First comes PMS. PMS stands for premenstrual syndrome. An estimated 80% of women suffer from PMS. PMS can manifest itself in many different ways: headaches, intestinal problems, joint pain, mood swings, etc.
  • You may also have hormonal acne.

4. Arrival of periods

The first day of the periods cycle also marks the beginning of the follicular phase. If your periods arrives, this means that the egg has not been fertilized this month. The lining of the uterus, called the endometrium, will then disintegrate, and this is where bloody discharge will appear. Menstrual flow is also made up of uterine mucosa. periods , their frequency and pain vary from one woman to another. Some women experience heavy flow , while others experience light flow. Bleeding lasts from 3 to 7 days most of the time.

During periods, you may experience various symptoms, such as menstrual cramps, abdominal pain, migraines etc...

How do you calculate the length of your menstrual cycle?

Knowing your menstrual cycle and when your periods will fall or when you are most likely to become pregnant is very practical. 

What day does periods arrive?

On average, a cycle lasts 28 days. The arrival of the periods marks the beginning of a new cycle and the end of the previous one.

To better anticipate the arrival of your periods, you can note and count the days in a menstrual cycle calendaror use a menstrual cycle tracking application.

What should I do if I have an irregular female cycle?

Irregular cycles can be a heavy mental burden for those who suffer from them. 

It's normal for your cycles to be irregular when you first start menstruating: your body needs to adapt to the hormonal changes. After 1 year, your cycle is usually regular.

Of course, there are periods in life when periods can become more irregular: we're thinking in particular of pregnancy and breastfeeding, but also of periods of stress.

So there are many factors in our lives that can influence the regularity of your periods. If your cycles are generally irregular, consult your doctor: it could sbe a deeper problem, such as PCOS

When is the best time to get pregnant?

Ovulation is when you have the best chance of getting pregnant. Ovulation generally occurs on the 14th day of the cycle. In fact, while the length of the follicular phase (before ovulation) varies, the luteal phase always lasts 14 days.

So, your most fertile time is between the 4th day before ovulation and the day after ovulation. In fact, since spermatozoa have a life expectancy of 5 days, you can get pregnant from intercourse in the days leading up to ovulation.

How do you know if you want to? As ovulation generally takes place around the 14th day of the cycle, you can start by counting on a calendar, or using a cycle-tracking application. Ovulation then leads to a number of symptoms (more or less noticeable depending on the individual). For example, you may feel

  • a feeling of heaviness and pain in the lower abdomen (on the side where the ovum is released)
  • bloating
  • a change in cervical mucus: secretions tend to become egg-white-like: more slippery and translucent
  • increased libido
  • a rise in your body temperature
  • some women also experience spotting (light blood loss) during ovulation.

What impact does the menstrual cycle have on daily life?

As explained above, the menstrual cycle is broken down into several major moments, all guided by hormonal changes. And hormonal fluctuations have a global impact on your body, mind and so on.

For example, during the first phase of the menstrual cycle, symptoms such as fatigue and sleep disturbance are common.

During the follicular phase (after periods and before ovulation), your libido may increase.

And during the luteal phase, the famous PMS (pre-menstrual syndrome) takes place. 80% of women are affected by PMS, to varying degrees of intensity.

PMS manifests itself in different ways for different women, but here are the most common symptoms:

  • mood swings
  • irritability
  • fatigue
  • heightened sensitivity
  • sleep disorders
  • anxiety
  • stress
  • sadness

In some severe forms of PMS, known as premenstrual dysphoric disorder (PMDD), symptoms are so severe that they lead to suicidal thoughts, depressed mood, etc. This disorder affects 3% to 8% of women.


Menstrual cycle FAQs

How can I tell if my menstrual cycle is 28 or 21 days long?

Cycle length varies. If your periods arrive after 21 days, your cycle lasts 21 days. If your periods arrive after 28 days, your cycle lasts 28 days.

How can I calculate my menstrual cycle?

There are several ways to keep track of your menstrual cycle: simply note the days of your periods in your calendar. Alternatively, there are mobile applications that allow you to track your cycle according to the date of your periods, your feelings, your presumed ovulation date etc... Handy for planning your vacations or anything else!

Can I get pregnant right after my periods ?

It's unlikely that you'll get pregnant just after periods. But it's not impossible: if your cycle is very short and ovulation takes place just after periods, if you have unprotected sex, you run the risk of becoming pregnant.


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