Cervical mucus in detail to identify the fertile days of the menstrual cycle

A very detailed explanation of how the hormones that regulate female fertility and the production phases of cervical mucus work.

When you learn to recognize cervical mucus and the sensation associated with it, a world opens up that allows you to understand our fertility without particular difficulties. All it takes is a little practice and patience, and it costs nothing.

The explanation you find here is complete and long. If you want you can read the simplified explanation of the Billings method (cervical mucus) .

You can even put it into practice right away, perhaps with the help of the leak checker and basal body temperature tool .

Everything that happens in our body and therefore also fertility, is precisely regulated through a series of commands and responses between the various organs of the body.

The messengers that carry information and “directives” are hormones .

In particular, the reproductive organs of women (uterus, ovaries, neck of the uterus) are subject to the action of two main hormones: estrogen and progesterone .

What follows is a very detailed explanation of how these hormones work, how they regulate fertility and the menstrual cycle and, consequently, what effects they have on a woman’s body, in order to be able to interpret them.

Production of estrogen and progesterone

To make things more complicated, the production of these hormones is regulated by other hormones that are produced in the brain ( LH and FSH ) which act directly on our ovaries.

Estrogens and progesterone act not only on the endometrium to allow for the creation of that favorable environment for the implantation of any conceived embryo, but also on the neck of the uterus (or also called cervix ).

Before fertile days

Before the fertile phase of each menstrual cycle begins, the neck is closed by a mucous plug which does not allow the passage of sperms but also of pathogens.

The vaginal environment is also unfavorable to their survival. The mucus present at this juncture is called G-mucus and is produced by the crypts found at the lower opening of the cervix (see image at right).

At the level of the neck of the uterus there are “crypts” in which the spermatozoa can “stay” after intercourse which took place at the beginning of the fertile phase, to then resume their journey when the mucus allows them to pass between its meshes (i.e. when begins to become more elastic and streamlined).

Variation of mucus in the fertile period

Cervical mucus varies greatly in appearance and consistency in the fertile period and consequently also the sensation that one has at the vulvar level is closely related to cervical mucus.

This variation is typical of every woman and every woman learns to recognize the changes that repeat themselves cycle after cycle.

It would be advisable to observe a month of abstinence from sexual intercourse and intimate contacts in order to be able to take note of the changes to the cervical mucus that are observed at the vulvar level and of the sensations that are experienced. This is to be able to recognize the mucus in all its variations without external interference.

Mucus has a specific composition: water (92% in the non-fertile period and 98% in the fertile period), glycoproteins, amino acids, sugars, electrolytes and proteins of various kinds.

The mucus works as a sort of filter whose meshes are thick and hostile in the non-fertile period, while in the days of fertility they favor the passage and nourishment of sperm, especially those of good quality.

Types of mucus and stages of production

G- mucus : This is a thick-meshed mucus that forms a barrier at the bottom of the cervix. Produced in the pre-ovulatory period (follicular phase), before the start of the fertile phase

G+ mucus : thick-meshed mucus, produced in the post-ovulatory (luteal) phase and thick-meshed that prevents the passage of sperm. G- and G+ mucus are produced at the bottom of the cervix.

L mucus: it is produced by the crypts of the entire cervix, throughout the fertile phase. It is a looser-meshed mucus that allows you to select the best spermatozoa by eliminating the low quality ones. It therefore allows only the best sperm to fill the S crypts.

Mucus S : It is produced near the peak of estrogen in the fertile phase and up to 3 days after ovulation. The crypts that secrete this mucus are found in the upper half of the cervix. This mucus nourishes the good quality spermatozoa (already selected from the mucus L) and directs them towards the crypts S where they “stay”.

P mucus: There are different types of P mucus and the most important are:

• P2 mucus : has the task of liquefying the G- mucus at the beginning of the fertile phase under the stimulus of estrogens
• P6 mucus , produced in the vicinity of the LH peak. Together with the mucus Z, it has the task of thinning the mucus (especially the mucus L). In this way the spermatozoa that were in the S crypts can continue their journey through a mucus with a large mesh and favorable for their passage. The mucus has become stringy and watery and this wet sensation is noticeable on the vulvar level.

Mucus Z : produced at the level of the isthmus (figure 2). With the P6 mucus it has the function of thinning the L mucus.

Mucus F: does not have a specific role

Change in mucus towards ovulation in an average 28 day cycle

Attention: indicative timing and not applicable to every woman.

6 days before ovulation estrogen is low and the cervix is ​​closed by the mucus plug G-. You are not fertile yet.

5 days before the fertile phase begins: the P2 mucus fluidifies the G- mucus which melts and comes out together with the L mucus. Sperm cells can now enter the cervix. At this point we no longer feel dryness at the vulvar level

4 to 1 day before ovulation: Estrogen increases, L mucus increases, S mucus begins and increases, P mucus becomes present at the time of LH surge a few hours before ovulation. All this can be seen at the vulvar level with the mucus gradually becoming less dense and one-two days before the peak it becomes stringy and watery . The consequent sensation is that of slipperiness (lubricated) due to the effect of the mucus P which thins the mucus L and S.

Ovulation imminent (day 0) : estrogen is high (Figure 4) and conditions are the most favorable for sperm to travel to the fallopian tubes.

Days +1, +2 and +3 days after ovulation: the formation of G+ mucus begins which, under the effect of progesterone, closes again the access to the neck of the uterus. Given that ovulation can occur on day zero or on days 1 or 2 and given that the egg cell lives for a maximum of 24 hours, conception is still possible up to the fourth day. On days 1, 2 and 3 the feeling is dry at the vulvar level even if you are still fertile for the reasons just mentioned.

We now therefore know that everything we see and hear at the vulvar level in the days preceding ovulation is due to the secretion of these crypts which act under hormonal and nervous stimulation .

The appearance of mucus and its changes are a mirror of how our fertility works.

For those who take the pill

Those who take the pill for years, after having stopped taking it, may have difficulty noticing the cervical mucus as the crypts have long been “silenced” by the effect of the drug, in some cases permanently.

Learn the Billings Ovulation Method

In Italy, located in regions and provinces, there are several teachers of natural methods who teach couples free of charge and the use of the Billings Ovulation Method (MOB) which is based on the daily registration of the symptoms of cervical mucus, to get pregnant or to avoid it.