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 mean something to you but you don't know exactly how they interact with each other and on your body to shape the rhythm of your menstrual cycle ? We 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:
- Follicle stimulating hormone (FSH)
- Luteinizing (LH)
Estrogens are a group of steroid hormones responsible for many important functions in the body, especially in women. They are mainly produced by the ovaries, although small amounts are also secreted by the adrenal glands and by fat cells.
The role of estrogens
Estrogens are present in both men and women, although they are present in greater quantities in women in whom they have 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, fat distribution, particularly in the thighs, buttocks and stomach;
- 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 in order to accommodate a possible embryo in the event of conception.
- Bone Health (M and F): Estrogen helps maintain bone density and prevent bone loss. They play a role in regulating the balance between bone formation and breakdown.
- Metabolism (M and F): Estrogens influence metabolism, including the regulation of cholesterol levels and body fat distribution. They also impact insulin sensitivity. This is one reason why women may experience food cravings and/or loss of appetite during the luteal phase, when estrogen levels vary 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 have effects on the central nervous system and may influence cognition, mood, and brain function. They have also been associated with 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 in people who menstruate during menstruation.
Estrogen levels increase during the follicular phase , under the influence of the growth of the egg within the dominant ovarian follicle. In addition to having a role in the release of the mature egg, it stimulates the growth of the uterine lining during the follicular phase and at the beginning of the luteal phase in order to accommodate a possible embryo in the event of conception.
If no pregnancy occurs, estrogen levels gradually decline at the end of the luteal phase. Its drop (concomitant with the drop in progesterone) triggers periods. At the same time, the joint decline in progesterone and estrogen levels signals to the pituitary gland that it needs to release LH and FSH again. A new menstrual cycle begins.
Influence of estrogen on the body and mood
Estrogen, as a hormone that varies wildly in the female body during menstrual cycles, has been linked to various effects on mood and mental health. However, it is important to note that the relationship between estrogen and mood is complex. This can vary greatly from person to person depending on many factors, including individual hormonal levels, medical history, social and psychological context… That is, whether estrogen and its variation can impact the body feminine and mood, it would be wrong to attribute all the discredit to them.
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 disorders linked to menstrual cycles: On the other hand, higher levels of estrogen can lead to greater irritability. If you're in a moody mood every time your period approaches, it's possible that you're hyperestrogenic and your body and mind aren't handling it well.
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 in preparing the uterus for possible pregnancy.
The role of progesterone
Just like estrogen, progesterone is present in both men's and women's bodies. In menstruating people, it has the particularity of fluctuating enormously 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 turns into the corpus luteum, which produces progesterone. Like estrogens, progesterone acts on the uterine mucosa, making it thicker and 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 holding the endometrium in place for the developing embryo;
- 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 miscarriage;
- Changes in cervical mucus: Progesterone makes cervical mucus thicker and less permeable to sperm, which reduces the chances of conception during the period when the uterus is preparing for 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 (notably prolactin) to prepare the breasts for milk production;
- Bone Health (M and F): Like estrogen, progesterone helps maintain bone density and prevent bone loss and osteoporosis;
- Metabolism (M and F): Progesterone influences metabolism, and in particular 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 start 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 the 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 implantation of an embryo in the event of conception.
If fertilization occurs, the embryo produces the hormone human chorionic gonadotropin (hCG), which keeps the corpus luteum producing progesterone to support the pregnancy. It prevents uterine contractions and allows the fertilized egg to settle in the uterus. In contrast, if no fertilization occurs, the corpus luteum stops producing progesterone as it decreases. The drop in progesterone levels (which follows the drop in estrogen levels) triggers the disintegration of the uterine lining, leading to menstrual bleeding.
The joint 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 start of a new menstrual cycle .
Influence of progesterone on the body and mood
If estrogen fluctuations mainly have effects on the morale of menstruating people, progesterone plays a role on the body and mood.
The effects of progesterone changes on the body are:
- Effects on the breasts: Progesterone may cause the mammary glands to increase in size and prepare the breasts for milk production in anticipation of lactation. If you have the feeling that your breasts are swelling during the luteal phase, you have found the culprit!
- Metabolic Effects: Progesterone may also have a mild thermogenic effect, increasing basal body temperature during the luteal phase of the menstrual cycle. The night sweats, the feeling of being boiling, the hot flashes... it's her!
- Menstrual cramps: Progesterone has the role of limiting contractions of the uterus to allow the fertilized egg to settle there. A progesterone deficiency could be the cause of the pain you feel every 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 the regulation of mood and anxiety. Present in large quantities in the body (hyperprogesteronemia), progesterone will have calming or even stoning/tiring effects, whereas in too small a quantity, it can lead to greater mood swings.
Generally speaking, you will have understood: estrogen and progesterone work together. The imbalance of one hormone relative 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 the LH
The 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 testicles to produce testosterone, the male sex hormone. Testosterone is essential for the development and maintenance of male sexual characteristics, as well as 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 has the effect of transforming the empty ovulatory follicle into the corpus luteum which produces progesterone. Even more, LH production is regulated by a hormonal feedback mechanism. When estrogen (or testosterone, in men) levels 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 smooth running 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 for 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 seeking to conceive to determine the most fertile time of their cycle (especially for women with irregular cycles ).
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 is the start of the follicular phase and a new cycle. In this, LH plays a role in regulating the body's hormones.
Influence of LH on the body and mood
Although 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 can be noted that, because it has a direct role in the regulation of sexual 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 hormones. sexual (mood disorders, depressive states, low or excessive libido, etc.).
Follicle-stimulating hormone (FSH)
Follicle-stimulating hormone (also called FSH) is a hormone produced by the pituitary gland, like LH. And like the latter, FSH plays an essential role in the regulation of reproductive function in men and women.
The role of FSH
The 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.
- Production of 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 H): FSH plays a key role in regulating the levels of other sex hormones. In women, it is its increase during the follicular phase which increases estrogen and then progesterone levels. When levels of estrogen and progesterone in women, or testosterone in men, reach a certain threshold, they send signals to the pituitary gland to increase or decrease FSH production.
FSH finally has a role at the medical level because it is a good indicator of fertility in individuals, men and women. Blood FSH levels can be used to assess ovarian function in women, including determining egg reserve. High FSH levels may indicate decreased ovarian function. In men, high FSH levels can indicate problems with sperm production.
FSH in the menstrual cycle
FSH also has 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 leads to 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 peak (just like the LH peak) 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. It's a new cycle.
In summary, FSH is responsible for stimulating the growth of ovarian follicles, estrogen production, and ultimately ovulation during the follicular phase of the menstrual cycle. Precise regulation of FSH is essential to ensure adequate 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. Its role in the regulation of sexual hormones being direct, a disruption of FSH can cause various problems linked to the lack or excess of sexual hormones (mood disorders, depressive states, low or excessive libido, etc.).
A little reminder of the 4 phases of the menstrual cycle
Rhythmized by hormones, the menstrual cycle is often presented in four phases . Let's discover these together as well as the role of the 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 corresponds to the follicular phase. This is the phase during which the eggs grow in the ovarian follicles. It begins at the same time as the menstruation 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 the hormone estrogen .
The ovulatory phase or ovulation
The second phase of the menstrual cycle corresponds to the ovulation phase. It consists of the release of the mature egg by the ovarian follicles. The egg then moves through the fallopian tubes towards the uterus.
At the hormonal level, it is the peak of luteinizing hormone that releases the mature egg from the dominant ovarian follicle. At the same time, estrogen levels are always very high and prepare the body for potential fertilization.
The luteal phase
The luteal phase is the third and penultimate phase of the menstrual cycle. If the follicular phase corresponds to the moment when the egg matures in the ovaries, the luteal phase corresponds to the moment when the whole body prepares for fertilization of the egg and therefore for pregnancy. The walls of the uterus are adorned with the endometrium, the uterine lining which develops to facilitate the implantation of the egg in the event of fertilization.
At the hormonal level, this phase is marked by a significant variation in hormone levels. At its beginning, just after ovulation, the estrogen level is very high and the progesterone level increases rapidly : the latter is secreted by the corpus luteum which replaces the dominant follicle emptied of its egg. Progesterone works 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 takes place, the levels of the hormones progesterone and estrogen gradually decrease. This triggers the shedding of the uterine lining and the expulsion of the egg. These are the rules.
The last phase of the cycle corresponds to menstruation. It takes place when the body realizes that the egg has not been fertilized: it expels the unfertilized oocyte as well as the endometrium. This phase begins at the same time as the follicular phase and thus represents the start of a new menstrual cycle.
At the hormonal level, this phase corresponds to a period when all female hormone levels are very low : progesterone and estrogen levels have fallen, then FSH and LH levels slowly rise to help new eggs grow… c It's the follicular phase that begins again.
Hormonal imbalance and menstrual cycles
Because hormones are essential for organizing menstrual cycles, hormonal changes and imbalances are often the cause of variations within menstrual cycles . They can be of natural origin (such as puberty or menopause), caused by an illness or even linked to lifestyle.
Natural hormonal imbalance
At puberty, sex hormones increase significantly. The body begins to release eggs, which triggers the menstrual cycle: these are the first periods. They generally take place 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 breast feeding
During pregnancy, the fertilized egg attaches to the uterine wall. The 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 the periods can continue until full term). The menstrual cycle stops and generally only resumes after breastfeeding: prolactin, a hormone which stimulates the mammary glands to produce breast milk, generally has the effect of blocking the resumption of the menstrual cycle until stopping breastfeeding.
Menopause is marked by a gradual decrease in estrogen. It generally occurs between the ages of 45 and 55. Ovulation becomes more irregular as estrogen drops and may eventually cease. This results in irregular cycles and then the complete cessation of menstruation.
Hormonal imbalance linked to diseases
If the life stages of menstruating people are marked by hormonal fluctuations which influence their menstrual cycle, these fluctuations can also be caused by illnesses. If you notice sudden changes in your menstrual cycle for no apparent reason, it may be worth seeing a doctor to talk about it. In light of your medical situation, he may carry out additional examinations if he deems it necessary.
Polycystic Ovary Syndrome (PCOS)
Polycystic ovary syndrome (PCOS) is an endocrine disorder that results in 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 hinder the ovulation process, leading to irregular cycles or even the absence of ovulation (anovulation). PCOS affects around 10% of women, but its symptoms vary greatly from one person to another.
The thyroid is an endocrine gland located at the base of the neck, in front of the trachea. It produces hormones essential for the regulation of metabolism, growth and development. It also influences sex hormones and disorders in its functioning can have an effect on menstrual cycles.
Hypothyroidism (underactive thyroid), the release of thyroid hormone is reduced. This dysfunction can lead to elevated levels of prolactin, the lactation hormone, which can inhibit ovulation.
In the case of hyperthyroidism (overactive thyroid), the balance of sex hormones can be significantly 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 abrupt and more or less constant, in menstrual cycles.
- Stress: In situations of stress, whether occasional or chronic, the body secretes several hormones, such as adrenaline, norepinephrine and cortisol. The latter can interact with the hormones which organize the menstrual cycle and thus modify it in a more or less brutal way.
- Rapid weight loss: In the event of a significant calorie deficit, the body can stop the production of sex hormones. It pauses. This is why people suffering from anorexia also suffer from amenorrhea (stopping of periods).
- Rapid weight gain, obesity: Fat cells generate androgen (male) hormones which can interfere with the functioning of sex hormones which affect the menstrual cycle. This can lead to more irregular cycles.
- Intensive sports practice: Caloric deficit and intensive sports practice act on sexual hormones. The menstrual cycle may be disrupted. Several high-level athletes suffer from amenorrhea (stopping of periods).
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 experience it very well, others can suffer from it. We are thinking here of premenstrual syndrome (PMS) and its more severe form, premenstrual dysphoric disorder (PMDD).
What are PMS and PMDD?
PMS and PMDD refer to all the symptoms experienced by menstruating people as they approach the menstrual phase, during the luteal phase.
Premenstrual syndrome (PMS) is a set of physical and emotional symptoms that occur in some women during the luteal phase. PMS can start just after ovulation and last the entire luteal phase or only last a few days: it varies greatly. This disorder is common but every woman experiences it differently, in terms of severity and types of symptoms experienced.
Symptoms of PMS may include:
- Emotional symptoms: Irritability, unstable mood, depressive episodes or even depression, anxiety and increased anxiety attacks, mood swings, increased sensitivity, difficulty concentrating, problems falling asleep and sleeping;
- Physical symptoms: Intestinal disorders (bloating, constipation and diarrhea), menstrual cramps, hormonal migraines, muscle or joint pain, fatigue, water retention, sore breasts, increased appetite, acne, etc.
Hormonal fluctuations linked to the menstrual cycle would be the main cause of these symptoms (although other elements come into play, such as heredity, diet, etc.) which differ greatly depending on women and their menstrual cycles. Thus, a majority of women do not experience the same menstrual symptoms throughout their life.
Premenstrual dysphoric disorder (PMDD) is also known as premenstrual dysphoric syndrome (PMDS). 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 causing PMS and PMDD: what the studies say
Current studies show that SPM and PMDD may occur in part due to greater sensitivity to hormonal variations. We mentioned it in this article: estrogen and progesterone levels fluctuate enormously during the menstrual cycle (it is even thanks to these fluctuations that the cycle works!). However, a strong sensitivity to these variations could explain the development of PMS.
We thus distinguish two types of PMS:
- Explosive PMS: Painful periods, swelling (water retention, swollen and painful breasts, bloating and intestinal disorders), night sweats, migraines and acne, mood disorders... The combination of these symptoms suggests hyperestrogenism ( too much estrogen compared to progesterone);
- PMS down: on the contrary, if your PMS is characterized more by fatigue, a lack of energy, motivation and libido, your symptoms are more reminiscent of hyperprogesteronemia (progesterone in too large a quantity compared to the estrogens).
What to do if you have PMS?
Before any self-medication, start by consulting your doctor and/or your gynecologist . Depending on your symptoms and your 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, installing an implant, etc.) and to respond directly to the symptoms ( pain medication against menstrual cramps and migraines, antidepressants against mood fluctuations, 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 oil for painful periods from Nidéco , the natural cure homornal dysregulation from Miyé , even 20% CBD oil against pain and stress linked to menstruation .
Among them, the Bluetens device, a medical device which naturally relieves pain thanks to electrostimulation:
Finally, know that like menstrual cycles which 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 action allows you to better experience your cycle and its various symptoms. Hormonal fluctuations and hormonal imbalances can cause specific problems that are not always easy to deal with. It is all the more complicated because menstrual cycles continually recur throughout the life of menstruating people. If you encounter specific difficulties or have any questions, do not hesitate to consult your general practitioner or gynecologist. If they think it is necessary, they can refer you to an endocrinologist, the professional specialized in the analysis of hormones.
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