Pregnancy project: everything you need to know about the luteal phase

The luteal phase

Welcome to the fascinating world of the luteal phase, a crucial stage of the menstrual cycle that is often overlooked.
The female hormonal cycle includes 4 major phases: menstruation, the follicular phase (pre-ovulatory), ovulation, then the luteal phase (post-ovulatory). Understanding this final phase is not only an asset for those looking to conceive, but for all women wanting to take control of their reproductive health.

The luteal phase deciphered

The luteal phase is therefore the post-ovulatory period of the menstrual cycle. This is the moment when the egg released during ovulation awaits the possibility of being fertilized. The follicle that released the egg turns into a structure called the corpus luteum. This metamorphosis triggers the production of progesterone, a key pregnancy hormone.

According to one study , the average length of the luteal period is 14 days, but it can last between 11 and 17 days. Each woman is unique and has her own hormonal balance which is essential to understand in order to know how to interpret her ovarian cycle.


The corpus luteum: the main player in the luteal phase

During the luteal phase, the corpus luteum comes into play and will play a crucial role in maintaining a potential pregnancy. Its name comes from its characteristic yellow color, secreted by a pigment, lutein.

The process of corpus luteum formation begins when a mature ovarian follicle releases an egg during ovulation. After the release of the egg, the empty follicle undergoes a transformation under the influence of luteinizing hormone (LH) produced by the pituitary gland. This transformed follicle becomes the corpus luteum, which is an active source of hormone production.

The primary role of the corpus luteum is to secrete hormones, mainly progesterone. Progesterone prepares the uterine lining by making it thicker, creating an environment conducive to implantation of a fertilized egg. If fertilization does not occur, the corpus luteum declines, causing progesterone levels to decrease and triggering the start of the menstrual cycle.

In pregnancy, the corpus luteum continues to produce hormones for the first few weeks, providing essential support for the pregnancy until the placenta takes over this function.


The course of the luteal phase

Biological and hormonal events

The concentration of progesterone reaches its peak during the luteal period, which has 3 major consequences:

  • The temperature curve increases, a sign that ovulation has taken place.
  • The white discharge that you observed during ovulation, i.e. cervical mucus, disappears.
  • The cervix closes and hardens.

The luteal period is also accompanied by various physical symptoms which may vary from woman to woman. Some women may experience mild cramping, sore breasts, or subtle mood changes. Others notice an increase in appetite and specific food cravings during this time.

The luteal phase in the event of fertilization

In the event of fertilization, the egg migrates towards the uterus and implants itself in the prepared mucosa. The embryo then produces the hormone hCG, or chorionic gonadotropin, which will then be secreted by the placenta. hCG maintains the activity of the corpus luteum, which continues to produce progesterone, providing essential hormonal support for the emerging pregnancy until the placenta takes over this function. It is this specific hormone, the "pregnancy hormone", that is detected by pregnancy tests , to confirm conception.

The luteal phase without fertilization

On the other hand, if the egg is not fertilized, the corpus luteum begins to decline. Decreased hormone levels, particularly progesterone, resulting from breakdown of the corpus luteum lead to changes in the uterine lining. This mucous membrane, which has been thickened to accommodate a possible embryo, not being necessary, begins to disintegrate.

This process marks the start of menstruation, where the endometrium, the lining of the uterus, is expelled from the body in the form of menstrual bleeding. This signals the start of a new menstrual cycle, with the start of a new follicular phase and the development of a new ovarian follicle in preparation for the next ovulation. Thus, the luteal period ends, and the body prepares for a new cycle of conception opportunities.


The luteal phase and basal body temperature

One of the major (and easiest to identify) symptoms of the luteal phase is therefore the slight increase in basal body temperature, after ovulation due to increased production of progesterone, usually between 0.3 to 0, 6 degrees Celsius. This temperature will remain higher until the arrival of your period, then it will return to a normal curve.

If you are planning to become pregnant, monitoring your basal temperature curve can therefore be a reliable method to predict ovulation and help you detect your fertile window.

If you become pregnant, your basal body temperature may remain high, even after your period is due.


Problems associated with the luteal phase

The luteal phase is particularly monitored in women who are having difficulty conceiving or who are experiencing recurrent miscarriages. In such cases, the first step is to carry out a fertility check-up, in order to detect possible ovulation disorders or hormonal imbalance . This will make it possible to determine whether longer or shorter luteal phases are responsible for disrupting fertility.

Luteal insufficiency

Luteal insufficiency, or short luteal period, occurs when there are less than 11 days between ovulation and the first day of the next period. Why is too short a luteal phase a problem? The level of progesterone produced by the corpus luteum is then often not sufficient and the uterine lining has not had enough time to thicken sufficiently. If fertilization has occurred, the fertilized egg will not have time to implant before the body triggers the next period, which will trigger a miscarriage (or terminated pregnancy).

This luteal insufficiency can have several causes, including hyperestrogenism (i.e. excess estrogen), hypothyroidism or even a hormonal imbalance, which is frequently encountered in women suffering from polycystic ovary syndrome. (PCOS).

This same hormonal imbalance can conversely lead to a luteal period that is too long, that is to say more than 17 days. However, if you still do not have your period 16 to 17 days after your ovulation, we recommend that you first take a pregnancy test.


Calculate and optimize your luteal phase

In order to better understand your cycle, there are now many tools that can become valuable. Cycle tracking apps, ovulation tests and symptom monitoring can be valuable in accurately calculating the luteal phase.

For those looking to optimize their reproductive health, a few lifestyle adjustments can be beneficial. Unsurprisingly, maintaining a healthy body weight, knowing how to manage stress and adopting a balanced diet are factors that can positively influence the duration and regularity of the luteal phase.

In conclusion, the luteal phase is much more than just a stage between two menstrual cycles. It is a time of preparation, subtle body communication and perfect synchronization. By understanding this phase, you can not only anticipate your cycle, but also maximize your chances of conception.


At Boome, we want to offer you fertility food supplements that respect your body and your needs, specially designed with ingredients of natural origin. Our products will accompany you through the different stages from your desire to have a child to the complete recovery of your postpartum period.

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