The menstrual cycle is a hormonal cycle by which the body produces hormones that contribute to the health and functioning of the body. It is a continuous, cyclical process that involves the maturation and release of eggs by the ovaries, the thickening of the lining of the uterus (the endometrium), which becomes rich in blood for a possible pregnancy, and the shedding of this layer of tissue midway through menstruation. A woman can have, in her reproductive life (the fertile years of her life), about 400 menstrual cycles. A menstrual cycle lasts, on average, 29 days, but can vary between 21 and 35 days and be considered healthy. The menstrual cycle begins on the first day of menstruation (with deep red blood flow) and ends one day before the next menstruation begins.
Perfect orchestra of hormones
The menstrual cycle is governed by hormones secreted by the pituitary gland (master endocrine gland located at the base of the brain) and the ovaries. It can be divided into two major phases: the follicular phase, in which the dominant hormone is estrogen (specifically estradiol), and the luteal phase, in which progesterone predominates.
Follicular phase
The first phase of the menstrual cycle is the follicular phase. It begins on the first day of menstruation and lasts until ovulation.
At this stage, the maturation process of the follicles in the ovaries begins with the action of FSH. The follicles are like “bags” that contain immature eggs.
In the follicular phase, the dominant hormone is estrogen, produced in the ovaries. Shortly after menstruation, estrogen levels rise. With an increase in the amount of this hormone, we can feel more active, full of energy and more energetic. Estrogen increases libido, improves disposition and mood. We can also feel happier, more dynamic and optimistic due to the increase in serotonin (which promotes feelings of well-being and happiness) and dopamine (which is associated with motivation and pleasure). The follicular phase is the spring of the menstrual cycle, its energy is one of expansion and the beginning of a new cycle. We can feel more confident and all our creative force is activated. This phase does not have a fixed duration, as it varies according to the time it takes for the follicle to grow and release the egg.
Estrogen stimulates the growth of the lining of the uterus and the production of cervical mucus. Cervical mucus is gel-like and can be felt by applying toilet paper to the vulva or inserting a finger into the vaginal canal. Its consistency can be creamy, sticky, stretchy or liquid. The closer we are to ovulation, the more liquid and clear it becomes, like egg white. Cervical mucus is a healthy fluid in our body, very different from discharge (yellowish or greenish), which indicates an infection. Cervical mucus has an alkaline pH, which allows sperm to quickly pass through the vaginal canal (which has a very acidic environment) and survive in the fallopian tubes for up to five days. Therefore, the presence of cervical mucus (of any type) indicates that we are fertile.
When we are close to ovulation, estrogen levels peak. The mucus becomes increasingly thin and our libido tends to increase! We may feel more beautiful, attractive and available.
Ovulation
When a follicle finally matures, the LH hormone sends a message to the ovary to release the egg. After leaving the ovary, the egg is captured by the fimbriae (which are like little fingers at the ends of the uterus) and carried to the fallopian tubes. At the time of ovulation, we can feel something like a slight pinch on one side of the ovaries. Egg release varies randomly from one ovary to the other. Occasionally, double ovulation may occur in a cycle, but if it does occur, it will always be within a period of up to 24 hours between one ovulation and the next. The egg remains in the body for up to 24 hours and, if fertilization does not occur, it disintegrates and is reabsorbed by the body.
The follicular phase lasts until ovulation. It’s common for ovulation to occur around day 14 or 15 of the menstrual cycle, but it can take a shorter or longer period to occur. It’s not possible to predict exactly when ovulation will occur, but we can sense (and record) signs from our bodies that indicate it’s approaching – such as the presence of cervical mucus, a change in the height of the cervix (when we’re fertile, our cervix becomes higher and softer, and the opening opens slightly (we can feel it by inserting a finger into our vagina during a shower, for example), we may feel wet and hornier! In the period around ovulation, we’re fertile. Being fertile means that if we have sex with a penis and vagina involved, we have a chance of getting pregnant.
Shortly after ovulation, we may notice the signs that indicate it has occurred, such as an increase in basal temperature, a change in the pattern of mucus - which now becomes dry - and the cervix - which becomes firm, low and closed.
Being fertile is different from ovulating! Ovulation is an event that lasts about 24 hours, but we are fertile for about 7 days, which is the period in which we produce moist cervical mucus that allows sperm to survive in our body.
Luteal phase
After ovulation, the second phase of the cycle begins, the luteal phase. This phase runs from the day of ovulation to the day before menstruation, when a new menstrual cycle begins. The empty follicle (the small sac containing the eggs) becomes a temporary endocrine gland, called the corpus luteum (hence the name “luteal phase”). The corpus luteum produces progesterone, which acts on the endometrium, making it even more nutritious and vascularized and allowing it to sustain a possible pregnancy. Its name indicates its main function: pro-pregnancy. Progesterone is a calming hormone, a mood regulator and has a “yin” quality. It acts by counteracting the action of estrogen (the hormone of the first phase of the cycle), so its action is very important for our health.
The action of progesterone raises body temperature. Therefore, monitoring basal temperature (body temperature at rest) throughout the cycle is the best way to confirm the onset of ovulation.
If the egg is not fertilized between ten and sixteen days after ovulation, the corpus luteum disintegrates and stops producing progesterone. The duration of this phase is determined by the lifespan of the corpus luteum, which never exceeds 16 days.
With the disintegration of the corpus luteum comes a drop in hormone levels (triggering mood swings around four days before menstruation), called Premenstrual Tension (PMT). This period can be perceived as a time of heightened creativity, where we can access deep emotions, have vivid dreams, and where we may feel less available to external demands and need more time to nurture ourselves. For many women, this can be a challenging period, especially in a world that requires us to always be productive, rational, and available. We can reclaim the potentials of this phase and appropriate them to rewrite the narratives that disqualify our bodies and the cycles of dominant culture.
Menstruation
The drop in progesterone stimulates the uterus to contract and shed its inner lining, produced in the previous cycle. Menstruation is the final event of this entire hormonal cycle and is composed of blood, cervical mucus, vaginal secretions and uterine lining. While this is happening in the uterus, the ovaries begin to mature their follicles again, beginning a new follicular phase. Therefore, the first day of menstruation is also the beginning of a new cycle.
During menstruation we may feel a decrease in energy and physical fatigue. Cramps and discomfort in the lower back or pelvic region are normal, but they should not be severe enough to require painkillers. If there is a lot of pain, it is an indication that something is not right.
Menstruation is the winter of the cycle, a time that demands rest and seclusion. If your reality allows it, rest and slow down during this period. In some countries in the Global North, there is a growing movement to pass laws that support menstruation, such as one that entitles women with heavy periods to three days of paid menstrual leave. In a society that demands constant productivity, taking a break can be a challenge, but it can also be a revolutionary movement of self-care that challenges hegemonic social impositions.
We can observe ourselves closely to understand how we feel at this moment in the cycle and thus receive the gifts that this phase brings us, which can be: calm, creativity, lucid dreams, visions, etc. Some traditions associate this phase with the archetype of the old woman or the witch, however, rather than adopting external models, our invitation is for you to observe yourself and understand how you are and how you feel during your period, in your own unique way.
Menstruation is never late! It always comes at a predictable period after ovulation. What can delay it is ovulation, which has no set date and is influenced by external factors: such as stress, medication use, travel, among others.
