How do hormones shape the rhythm of the menstrual cycle?

The menstrual cycle of menstruating people recurs every month throughout their fertile period, from puberty to menopause. The menstrual cycle is masterfully orchestrated by female hormones. Estrogen, progesterone, LSH : these hormone names ring a bell, but you're not sure exactly how they interact with each other and with your body to shape the rhythm of your menstrual cycle ? We'll talk about it in this article!

The main hormones involved in the menstrual cycle

Men and women share many hormones, but some are specific to their sexual characteristics. The so-called female hormones, involved in the proper functioning of the menstrual cycle , are as follows:

• Estrogens
• Progesterone
• Follicle-stimulating hormone (FSH)
• Luteinizing Hormone (LH)

Estrogens

Estrogens are a group of steroid hormones responsible for many important functions in the body, particularly in women. They are primarily produced by the ovaries, although small amounts are also secreted by the adrenal glands and fat cells.

The role of estrogens

Estrogens are present in both men and women, although they are present in greater quantities in women, where they play an important role in sexual development and the reproductive system.

• Sexual development (F): Estrogens are essential for the development of secondary sexual characteristics in females during puberty. They contribute to breast growth, hip development, and fat distribution, particularly in the thighs, buttocks, and abdomen;
• Menstrual Cycle and Reproductive System (F): Estrogens play a major role in regulating the menstrual cycle. They are responsible for the maturation of ovarian follicles and play a key role in the release of the mature egg. They stimulate the growth of the uterine lining to accommodate a possible embryo in the event of conception.
• Bone Health (M and F): Estrogen helps maintain bone density and prevent bone loss. It plays a role in regulating the balance between bone formation and breakdown.
• Metabolism (M and F): Estrogen influences metabolism, including the regulation of cholesterol levels and body fat distribution. It also impacts insulin sensitivity. This is one reason why women may experience food cravings and/or loss of appetite during the luteal phase, when estrogen levels fluctuate greatly.
• Cardiovascular System (M and F): Estrogens have beneficial effects on the cardiovascular system by helping to maintain the flexibility of blood vessel walls and promoting vessel dilation.
• Brain Function (M and F): Estrogens affect the central nervous system and can influence cognition, mood, and brain function. They have also been linked to the regulation of appetite and eating behavior. Again, this explains why their significant variation in the body can lead to mood changes or food cravings.

Estrogen in the menstrual cycle

Estrogen plays a major role in regulating the menstrual cycle. Estrogen levels vary greatly among menstruating individuals during the menstrual cycle.

Estrogen levels increase during the follicular phase , influenced by the growth of the egg within the dominant ovarian follicle. In addition to playing a role in the release of the mature egg, it stimulates the growth of the uterine lining during the follicular phase and early luteal phase to accommodate a possible embryo in the event of conception.

If pregnancy does not occur, estrogen levels gradually decline at the end of the luteal phase. This decline (along with the decline in progesterone) triggers menstruation. At the same time, the joint decline in progesterone and estrogen levels signals the pituitary gland to release LH and FSH again. A new menstrual cycle begins.

Influence of estrogen on the body and mood

Estrogen, as a hormone that fluctuates wildly in the female body during menstrual cycles, has been linked to various effects on mood and mental health. However, it's important to note that the relationship between estrogen and mood is complex. It can vary greatly from person to person depending on many factors, including individual hormone levels, medical history, social and psychological context, etc. In other words, while estrogen and its variation can have an impact on the female body and mood, it would be wrong to give them all the credit.

Here are some ways estrogen can influence mood and mental health:

• Depression: Women with lower than average estrogen levels are more likely to experience symptoms of depression. During the postpartum period and menopause, two periods marked by a significant reduction in estrogen levels, menstruating people are more likely to be exposed to depression ( menopausal blues , postpartum depression);
• Irritability and mood swings related to menstrual cycles: Conversely, higher estrogen levels can lead to increased irritability. If you're in a bad mood every time your period approaches, you may be experiencing hyperestrogenism , and your body and mind aren't handling it well.

⚡ Did you know that evening primrose oil can influence our menstrual cycle by helping to reduce the symptoms of premenstrual syndrome (PMS) and easing menstrual pain for some women, thanks to its action on estrogen levels?

Progesterone is a steroid hormone produced primarily by the corpus luteum in the ovaries in women. Its role is particularly important in regulating the menstrual cycle and preparing the uterus for a possible pregnancy.

The role of progesterone

Like estrogen, progesterone is present in both men and women. In menstruating individuals, its levels fluctuate greatly during the menstrual cycle and during pregnancy.

Here are the main roles of progesterone in the body:

• Menstrual cycle: Progesterone is involved in the second half of the menstrual cycle, called the luteal phase. After ovulation, the ovarian follicle that released the egg transforms into the corpus luteum, which produces progesterone. Like estrogen, progesterone acts on the uterine lining, making it thicker and more vascularized, to facilitate possible implantation of the embryo;
• Pregnancy support: If fertilization occurs, the developing embryo produces a hormone called human chorionic gonadotropin (hCG). HCG stimulates the corpus luteum to continue producing progesterone. This extra progesterone supports pregnancy by preventing the uterus from contracting and keeping the endometrium in place for embryo development;
• Prevention of uterine contractions: During the luteal phase and then during pregnancy, progesterone exerts a relaxing effect on the uterine muscles, thus preventing premature contractions which could lead to a miscarriage;
• Changes in cervical mucus: Progesterone makes cervical mucus thicker and less permeable to sperm, reducing the chances of conception during the time when the uterus is preparing for a possible pregnancy (the follicular phase);
• Effects on the breast: Progesterone is involved in the development of the mammary glands during pregnancy and lactation. It works in collaboration with other hormones (especially prolactin) to prepare the breasts for milk production;
• Bone Health (M & F): Like estrogen, progesterone helps maintain bone density and prevent bone loss and osteoporosis;
• Metabolism (M and F): Progesterone influences metabolism, particularly the regulation of body temperature. This is one reason why women may experience night sweats during the luteal phase or hot flashes during menopause.

Progesterone in the menstrual cycle

Progesterone plays a crucial role in a woman's menstrual cycle.

Generated in large quantities at the beginning of the second half of the cycle (during the luteal phase), it is present in small quantities during the follicular phase of the menstrual cycle. Following the release of the egg, the empty ovulatory follicle transforms into a corpus luteum. The latter generates progesterone: the progesterone level increases sharply .

At the beginning of the luteal phase, progesterone acts on the endometrium, making it thicker and more favorable for the implantation of an embryo in the event of conception.

If fertilization occurs, the embryo produces the hormone human chorionic gonadotropin (hCG), which maintains the corpus luteum's production of progesterone to support pregnancy. It prevents uterine contractions and allows the fertilized egg to implant in the uterus. Conversely, if fertilization does not occur, the corpus luteum stops producing progesterone as it decreases. The decline in progesterone levels (which follows the decline in estrogen levels) triggers the disintegration of the uterine lining, leading to menstrual bleeding.

The common decline in progesterone and estrogen levels triggers the occurrence of the next cycle: at the end of the luteal phase, the pituitary gland releases LH and FSH again, marking the beginning of a new menstrual cycle.

Diagram of the evolution of progesterone during the menstrual cycle

Influence of progesterone on the body and mood

While fluctuations in estrogen primarily affect the mood of menstruating people, progesterone plays a role in the body and mood.

The effects of progesterone fluctuations on the body are as follows:

• Effects on breasts: Progesterone can cause the mammary glands to enlarge and prepare the breasts for milk production in preparation for lactation. If you feel your breasts swell during the luteal phase, you've found the culprit!
• Metabolic effects: Progesterone can also have a mild thermogenic effect, increasing basal body temperature during the luteal phase of the menstrual cycle. Night sweats, feeling hot, hot flashes... that's it!
• Menstrual cramps: Progesterone's role is to limit uterine contractions to allow the fertilized egg to implant. A progesterone deficiency could be the cause of the pain you experience each month.

When it comes to mood, progesterone can influence the central nervous system , including receptors for neurotransmitters such as serotonin and GABA (gamma-aminobutyric acid). These neurotransmitters are involved in regulating mood and anxiety. When present in large quantities in the body (hyperprogesteronemia), progesterone will have calming or even dulling/tiring effects, while in too low a quantity, it can lead to more significant mood swings.

Generally speaking, you'll have understood: estrogen and progesterone work together. An imbalance of one hormone in relation to the other can lead to dysfunctions that we will see later.

Luteinizing hormone (LH)

Luteinizing hormone (LH) is a hormone produced by the pituitary gland, a small gland located at the base of the brain. It plays a crucial role in regulating the menstrual cycle in women and in reproductive function in both men and women.

The role of LH

LH has several functions:

• Menstrual cycle (F): LH is responsible for triggering ovulation, the process where a mature egg is released from the ovary.
• Testosterone (H) production: LH stimulates Leydig cells in the testes to produce testosterone, the male sex hormone. Testosterone is essential for the development and maintenance of male sexual characteristics, as well as for sperm production.
• Function in the regulation of sex hormones (F and H): LH plays a key role in regulating the levels of other sex hormones. In women, in addition to triggering ovulation, the LH surge acts to transform the empty ovulatory follicle into a corpus luteum that produces progesterone. Furthermore, LH production is regulated by a hormonal feedback mechanism. When estrogen levels (or testosterone, in men) reach a certain threshold, they send signals to the pituitary gland to increase or decrease LH production. This feedback is crucial for maintaining hormonal balance in the body.

LH in the menstrual cycle

Like all other hormones involved in the menstrual cycle, LH is absolutely essential for the proper functioning of the cycle.

Before ovulation, LH levels rise rapidly, causing the mature ovarian follicle to rupture and release the egg. LH is thus responsible for the release of the egg and therefore ovulation.

This LH surge is also known as the "preovulatory surge" and is an important marker of the optimal time for fertilization.
This is why LH tests exist: they are commonly used to detect the LH surge, which indicates the optimal time for ovulation. These tests can be used by women trying to conceive to determine the most fertile time of their cycle.

At the end of the luteal phase, when progesterone and estrogen levels drop in the body, they act as a trigger: LH begins to be produced again. This marks the beginning of the follicular phase and a new cycle. In this way, LH plays a role in regulating the body's hormones.

Influence of LH on the body and mood

While luteinizing hormone (LH) plays a crucial role in regulating the menstrual cycle in women, the influence of LH on mood is less documented and less clear than for other hormones such as progesterone or estrogen. However, it should be noted that, because it has a direct role in the regulation of sex hormones, a disruption in the functioning and release of LH in the body can be responsible for various problems linked to the lack or excess of sex hormones (mood disorders, depressive states, low or excessive libido, etc.).

Follicle-stimulating hormone (FSH)

Follicle-stimulating hormone (also known as FSH) is a hormone produced by the pituitary gland, like LH. And like LH, FSH plays a vital role in regulating reproductive function in both men and women.

The role of FSH

FSH has several functions:

• Menstrual cycle (F): FSH is involved in the development and maturation of ovarian follicles, which contain eggs. During the follicular phase of the menstrual cycle, FSH stimulates the growth of ovarian follicles and the production of estrogen. FSH helps select the dominant follicle that will reach full maturation and release an egg during ovulation. The other follicles regress.
• Sperm production (H): FSH plays a role in regulating sperm production in the testes. It stimulates Sertoli cells in the seminiferous tubules of the testes, which support sperm maturation.
• Function in the regulation of sex hormones (F and M): FSH plays a key role in regulating the levels of other sex hormones. In women, it is its increase during the follicular phase that increases estrogen and then progesterone levels. When estrogen and progesterone levels in women, or testosterone in men, reach a certain threshold, they send signals to the pituitary gland to increase or decrease FSH production.

Finally, FSH has a role in medicine because it is a good indicator of fertility in both men and women. FSH levels in the blood can be used to assess ovarian function in women, particularly to determine egg reserve. High FSH levels can indicate decreased ovarian function. In men, high FSH levels can indicate problems with sperm production.

FSH in the menstrual cycle

FSH also plays an essential role in the menstrual cycle.

At the beginning of the follicular phase, it begins to be produced by the pituitary gland in response to low levels of progesterone and estrogen . Its production causes the growth of several ovarian follicles. Under its action, only one follicle, the dominant follicle, matures, while the others regress. Their growth leads to the production of estrogen.

Then, at the end of the follicular phase, the FSH surge (just like the LH surge) triggers ovulation and the transformation of the empty dominant follicle into a corpus luteum. The latter produces progesterone during the luteal phase. Indirectly, FSH therefore initiates the increase in estrogen and progesterone in the body of menstruating people.

Finally, at the end of the luteal phase, when progesterone and estrogen levels drop because the egg has not been fertilized, FSH production begins again. This is a new cycle.

In summary, FSH is responsible for stimulating ovarian follicle growth, estrogen production, and ultimately ovulation during the follicular phase of the menstrual cycle. Precise regulation of FSH is essential to ensure proper follicular development and proper regulation of sex hormones throughout the cycle.

Influence of FSH on the body and mood

Like LH, FSH plays a key role in regulating the menstrual cycle in women, but its influence on mood and the body has been less studied than the influence of progesterone and estrogen. Since its role in regulating sex hormones is direct, a disruption in FSH can cause various problems related to the lack or excess of sex hormones (mood disorders, depression, low or excessive libido, etc.).

A quick reminder of the 4 phases of the menstrual cycle

Rhythmic with hormones, the menstrual cycle is often presented in four phases . (By the way, if you didn't know, women's hormonal cycles also influence mood .) Let's discover these phases together, as well as the role of different hormones in the different phases. To go further and better understand how the menstrual cycle works, discover our complete guide to menstrual cycles .

The follicular phase

The first phase of the menstrual cycle is the follicular phase. This is the phase during which eggs grow in the ovarian follicles. It begins at the same time as the menstrual phase.

During this phase, the hormones FSH (follicle-stimulating hormone) and LH (luteinizing hormone) are secreted by the pituitary gland (in the brain), their levels increase and they stimulate the ovaries to produce follicles. Each follicle contains an immature egg, but only one is dominant. This dominant follicle continues to grow and produces estrogen hormones .

The ovulatory phase or ovulation

The second phase of the menstrual cycle corresponds to the ovulation phase. Tounderstand what ovulation is : is the process in which a mature egg is released from an ovary, allowing its possible fertilization during the fertile period of a menstrual cycle. The egg then travels down the fallopian tubes toward the uterus.

Hormonally, it is the peak of luteinizing hormone that releases the mature egg from the dominant ovarian follicle. At the same time, estrogen levels remain very high , preparing the body for potential fertilization.

The luteal phase

The luteal phase is the third and penultimate phase of the menstrual cycle. While the follicular phase is when the egg matures in the ovaries, the luteal phase is when the entire body prepares for fertilization of the egg and therefore pregnancy. The walls of the uterus are covered with the endometrium, the uterine lining that develops to facilitate implantation of the egg in the event of fertilization.

Hormonally, this phase is marked by a significant variation in hormone levels. At its beginning, just after ovulation, estrogen levels are very high and progesterone levels increase rapidly : the latter is secreted by the corpus luteum, which replaces the dominant follicle that has been emptied of its egg. Progesterone acts by thickening the uterine lining and also has the effect of reducing uterine contractions, which keeps the endometrium in place and prevents premature bleeding. If no fertilization occurs, progesterone and estrogen hormone levels gradually decrease. This triggers the detachment of the uterine lining and the expulsion of the egg. This is menstruation.

Menstruation (periods)

The last phase of the cycle is menstruation. It occurs when the body realizes that the egg has not been fertilized: it expels the unfertilized oocyte along with the endometrium. This phase begins at the same time as the follicular phase and thus represents the beginning of a new menstrual cycle.

Hormonally, this phase corresponds to a period when all female hormone levels are very low : progesterone and estrogen levels have dropped, so FSH and LH levels slowly rise to make new eggs grow... this is the follicular phase starting again.

Hormonal imbalance and menstrual cycles

Because hormones are essential for organizing menstrual cycles, hormonal changes and imbalances often cause variations in menstrual cycles . These changes can be natural (such as during puberty or menopause), caused by illness, or lifestyle factors.

Naturally occurring hormonal imbalance

Puberty

During puberty, sex hormones increase significantly. The body begins to release eggs, which triggers the menstrual cycle: this is the first period. It generally occurs between the ages of 10 and 15 in young women. During the first cycles, the release of eggs can be irregular, making the first years of menstruation rather unpredictable.

Pregnancy and breastfeeding

During pregnancy, the fertilized egg attaches to the uterine wall. Female sex hormones then work to preserve the pregnancy and stop the menstrual cycle (except in rare cases, for example, during denial of pregnancy where periods may continue until term). The menstrual cycle stops and generally only resumes after breastfeeding: prolactin, the hormone that stimulates the mammary glands to produce breast milk, generally has the effect of blocking the resumption of the menstrual cycle until breastfeeding stops.

Menopause

Menopause is marked by a gradual decline in estrogen. It typically occurs between the ages of 45 and 55. Ovulation becomes more irregular as estrogen levels decline and may eventually cease. This results in irregular cycles and eventually the complete cessation of menstruation.

Hormonal imbalance linked to diseases

While the life stages of menstruating people are marked by hormonal fluctuations that affect their menstrual cycle, these fluctuations can also be caused by illness. If you notice sudden changes in your menstrual cycle for no apparent reason, it may be a good idea to consult a doctor to discuss them. In light of your medical situation, they may conduct additional tests if they deem it necessary.

Polycystic Ovary Syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is an endocrine disorder that causes symptoms such as irregular menstrual cycles, enlarged ovaries containing small cysts, and high levels of androgens (male hormones) in the body.
This hormonal abnormality can interfere with the ovulation process, leading to irregular cycles or even the absence of ovulation (anovulation). PCOS affects approximately 10% of women, but its symptoms vary greatly from person to person.

Thyroid diseases

The thyroid is an endocrine gland located at the base of the neck, in front of the trachea. It produces hormones essential for regulating metabolism, growth, and development. It also influences sex hormones, and disturbances in its function can affect menstrual cycles.

Hypothyroidism (underactive thyroid) reduces the release of thyroid hormone. This dysfunction can lead to elevated levels of prolactin, the breastfeeding hormone, which can inhibit ovulation.

In the case of hyperthyroidism (overactive thyroid), the balance of sex hormones can be severely disrupted, leading to irregular cycles.

Lifestyle-related hormonal changes and imbalances

Finally, lifestyle can also have an influence on the levels and types of hormones present in the body, leading to changes, more or less sudden and more or less constant, in menstrual cycles.

• Stress: In situations of stress, whether temporary or chronic, the body secretes several hormones, such as adrenaline, noradrenaline and cortisol. These hormones can interact with the hormones that regulate the menstrual cycle and thus modify it more or less abruptly. For example, you may have a longer menstrual cycle , or a shorter menstrual cycle . In short, stress can modify the length of your menstrual cycles .
• Rapid weight loss: In the event of a significant calorie deficit, the body can stop producing sex hormones. It goes into a pause mode. This is why people suffering from anorexia also suffer from amenorrhea (cessation of menstruation).
• Rapid weight gain, obesity: Fat cells generate androgen (male) hormones that can interfere with the function of sex hormones that affect the menstrual cycle. This can lead to more irregular cycles.
• Intensive sports practice: Calorie deficit and intensive sports practice affect sex hormones. The menstrual cycle can be disrupted. Many high-level athletes suffer from amenorrhea (cessation of menstruation).

PMS and PMDD: When hormones play tricks on us

Menstruating people, due to their hormones and their menstrual cycle, are therefore under the constant influence of their hormonal fluctuations . While some people cope very well with it, others can suffer from it. We are thinking here of premenstrual syndrome (PMS) and its more severe form, premenstrual dysphoric disorder (PMDD).

What is PMS and PMDD?

PMS and PMDD refer to the set of symptoms experienced by menstruating people as they approach the menstrual phase, during the luteal phase.

PMS

Premenstrual syndrome (PMS) is a group of physical and emotional symptoms that some women experience during the luteal phase. PMS can begin just after ovulation and last the entire luteal phase, or it can last only a few days—it varies greatly. It's a common condition, but every woman experiences it differently, both in terms of severity and the types of symptoms she experiences.

Symptoms of PMS may include:

• Emotional symptoms: Irritability, unstable mood, depressive episodes or even depression, anxiety and increased panic attacks, mood swings, increased sensitivity, difficulty concentrating, difficulty falling asleep and staying asleep;
• Physical symptoms: Intestinal problems (bloating, constipation and diarrhea), menstrual cramps, hormonal migraines, muscle or joint pain, fatigue, water retention, painful breasts, increased appetite, acne, etc.

Hormonal fluctuations related to the menstrual cycle are thought to be the main cause of these symptoms (although other factors come into play, such as heredity, diet, etc.), which vary greatly depending on the woman and her menstrual cycle. Thus, a majority of women do not experience the same menstrual symptoms throughout their lives.

The TDPM

Premenstrual dysphoric disorder (PMDD) is also known as dysphoric premenstrual syndrome (DPS). It is a severe form of premenstrual syndrome (PMS) and is characterized by emotional and physical symptoms that are more intense and disruptive than those experienced with PMS.

PMDD symptoms can be so severe that they interfere with daily life, relationships, and overall well-being. Hormonal fluctuations, particularly estrogen and progesterone levels, are thought to be a contributing factor to these symptoms.

Hormonal Fluctuations Cause PMS and PMDD: What the Studies Say

Current studies show that PMS and PMDD may occur in part due to a greater sensitivity to hormonal fluctuations. As we mentioned in this article, estrogen and progesterone levels fluctuate enormously during the menstrual cycle (they're actually what makes the cycle work!). However, a high sensitivity to these fluctuations could explain the development of PMS.

We thus distinguish two types of SPM:

• Explosive PMS: Painful periods, swelling (water retention, swollen and painful breasts, bloating and intestinal problems), night sweats, migraines and acne, mood disorders... The combination of these symptoms suggests hyperestrogenism (too much estrogen compared to progesterone);
• PMS down: on the other hand, if your PMS is characterized by fatigue, a lack of energy, motivation and libido, your symptoms are more likely to be hyperprogesteronemia (progesterone in too great a quantity compared to estrogen).

What to do if you suffer from PMS?

Before self-medicating, start by consulting your doctor and/or your gynecologist . Depending on your symptoms and problems, they will be able to offer you medical solutions or refer you to an endocrinologist, a doctor specializing in the functioning of hormones.

Currently, there is no specific treatment for PMS and its more severe form, PMDD. It is possible to act on your hormones and help them regulate themselves through hormonal contraception (taking the pill, inserting an implant, etc.) and to respond directly to the symptoms ( painkillers for menstrual cramps and migraines, antidepressants for mood swings, etc.). More and more natural solutions are available to support you in your menstrual cycles: do not hesitate to consult our specialized products on PMS and period pain , you will find Nidéco 's oil for painful periods , Miyé's natural cure for hormonal imbalance , even 20% CBD oil for pain and stress related to menstruation .

Among them, the Bluetens device, a medical device that naturally relieves pain through electrostimulation:

Finally, be aware that just like menstrual cycles vary over time and depending on the experiences you have (pregnancy, breastfeeding, illnesses, etc.), PMS and PMDD evolve.

Hormones play a crucial role in the menstrual cycle , and understanding their effects helps you better manage your cycle and its various symptoms. Hormonal fluctuations and imbalances can lead to specific issues that aren't always easy to deal with. This is made even more complicated by the fact that menstrual cycles recur continuously throughout the lives of menstruating individuals. If you experience specific difficulties or have any questions, don't hesitate to consult your general practitioner or gynecologist. If they deem it necessary, they may refer you to an endocrinologist, a professional who specializes in hormone analysis.