The Female Menstrual Cycle: Simply Explained with the 4 Seasons

Follicular phase, ovulation, cycle halves, luteal phase – WHAT? At least that is what I thought when I first dealt with women’s health and the female menstrual cycle.

Maybe you feel the same (then I’m relieved, because at first I found the topic really tricky 😜), and maybe you are just getting to know your body a little better. Then you are in the right place!

In this article we replace question marks with exclamation marks and focus entirely on you and your menstrual cycle. I also cover conditions like PMOS (formerly PCOS) and endometriosis, and missing ovulation and its possible causes. To me, that is simply part of the basics.

I am Lina, a state-certified nutrition consultant, health coach for women’s health and an expert in cycle loss.

What is the female cycle?

Behind the female menstrual cycle is a system cleverly devised by nature that prepares the body for a possible pregnancy month after month. The brain, ovaries and uterus work closely together for this, thanks to wonderful messengers, the hormones.

It begins with the first period (menarche) and continues until menopause. At least if an eating disorder does not get in the way, as it did for me: for years I had no period (hypothalamic amenorrhea) because of anorexic bulimia, and for a long time I fought against being a woman. But that is another story, which I tell you here.

A healthy cycle of an adult woman lasts 25 to 35 days on average, with 28 days being the average. On about 5 to 6 of those days a woman is fertile. Important to mention: you are individual, and so is your cycle. The most important thing is that your cycle feels good to you.

With a very long cycle of more than 35 days, however, PMOS should be ruled out, for example. A cycle without ovulation (anovulatory cycle), a very long follicular phase, for instance due to a thyroid condition, or the transition into menopause can also be behind it.

Very short cycles of less than 21 days also point to hormonal imbalances, for example a cycle without ovulation or a short follicular or luteal phase.

Behind all of this, and behind a missing period, there can be quite a few causes. Even gluten intolerance, malnutrition and nutrient deficiencies or stress on every level can be triggers. You can read which habits often slow your cycle down unnoticed in the 5 cycle killers.

But let’s start from the beginning. You now know that the cycle is there to prepare you for a pregnancy. It needs different phases and hormones, which we will now look at one by one. What helped me a lot: dividing the cycle into seasons. That is exactly what I want to pass on to you. Ready?

Winter (menstruation) → spring (follicular phase) → summer (ovulation) → autumn (luteal phase)

Phase 1: Your inner winter – the menstrual phase

Your period announces a new cycle! The day you get your period is cycle day 1 of your period week.

In the previous cycle, the body built up the uterine lining for a possibly fertilized egg. The job of menstruation is to shed it again. To do this, the body cuts off the lining’s blood supply, among other things, and the tissue is shed through the menstrual flow and the contractions of the uterus.

The body is usually busy with this for 3 to 7 days and mostly loses about 30 to 60 ml of blood. Reminder: every woman is different. Some bleed for 7 days, others for only 3, and still lose a similar amount of blood. None of that is better or worse.

Hormonally, things look pretty bleak during your period. Mood swings, cravings or headaches are not unusual because of the drop in hormones. Sex hormones are real superheroes and regulate so much more than just your cycle, and already in this phase estrogen slowly but surely starts to rise again.

Disorders in this phase of the cycle can include:

• Amenorrhea: missing period, as was the case for me for a long time
• Dysmenorrhea: painful period
• Hypermenorrhea: heavy blood loss (more than 80 ml)
• Hypomenorrhea: very light bleeding

Phase 2: Spring feelings – the follicular phase

The sun peeks out more often, flowers bloom and your mood lifts: welcome to the follicular phase! The first half of the cycle is in full swing and the hormone estrogen rises. The uterine lining starts building up again so that a fertilized egg could implant, and your body prepares for ovulation.

But estrogen isn’t everything. Follicle-stimulating hormone (FSH) from the pituitary gland also rises and makes several follicles mature in the ovary. A follicle is a small structure in the ovary in which the egg matures. Only one wins, the so-called Graafian follicle, whose egg is released at ovulation.

The follicular phase lasts about 14 days on average and is the part of the cycle that varies the most. If it is very long, the body needs more time for a follicle to mature, for example with stress, low energy, thyroid problems or PMOS. Ovulation then comes late or not at all. The balance of hormones matters too: estrogen dominance means that there is too much estrogen in the body relative to progesterone (relative estrogen dominance). Water retention, breast tenderness and mood swings can be signs of it. Conversely, estrogen deficiency can also mean that no ovulation takes place.

By the way, a period is NOT a reliable sign that ovulation has taken place.

Side note: endometriosis

Endometriosis is an estrogen-dependent condition: estrogen can fuel the growth of endometriosis lesions, while progesterone tends to counteract it. Too much estrogen relative to progesterone can therefore make symptoms worse.

With estrogen dominance or existing endometriosis, one important thing is to support the elimination of estrogen. The liver breaks estrogen down, and it is excreted via the gut and kidneys. Cruciferous vegetables like broccoli contain compounds that can support estrogen breakdown in the liver.

Also try to keep your exposure to pollutants as low as possible, and focus on good food quality and an overall anti-inflammatory, hormone-friendly diet with plenty of bitter compounds and different kinds of fiber. And don’t skip seeing your doctor!

Phase 3: Summer and sunshine – the ovulation phase

Also known as ovulation. Energy, glow and a good mood, that is what summer stands for. This is where the egg enjoys its big moment. About 24 to 36 hours pass from the rise in LH to ovulation. After that, the egg can only be fertilized for about 12 to 24 hours.

Around the middle of the cycle, estrogen reaches its peak. With that, the body signals to the brain that it is ready to release luteinizing hormone (LH).

LH ultimately gives the “GO!” for ovulation: the follicle bursts and releases the mature egg. It travels from the ovary into the fallopian tube, where it can be fertilized over the next 12 to 24 hours.

Did you know? Testosterone reaches its highest concentration around ovulation. In women, too, it increases libido and, just like the “female” sex hormones in men, is essential for a healthy body.

Signs of ovulation

• Cervical mucus: you notice much more cervical mucus, it resembles egg white and is stretchy, meaning it forms threads. This is not yet a sure sign of ovulation, but it shows that your body wants to trigger one soon.
• Basal body temperature: after ovulation it rises by about 0.2 to 0.5 degrees Celsius and ideally stays up until shortly before your period. You measure it in the morning before getting up, with a special thermometer. Important: the temperature only confirms ovulation afterwards.
• Cervix: around ovulation it is soft, sits higher and is slightly open, which makes it harder to feel. Admittedly, checking takes some getting used to and a bit of practice, but it honestly tells you so much about your own body!
• Mittelschmerz: a slight pulling can announce ovulation. On its own, though, like a period, it is definitely not a sure sign that it really happens.

The more of these four signs you notice, the more likely ovulation is.

No ovulation despite a period: possible causes

For ovulation to happen, the brain and ovaries need a finely tuned signal. Stress, low energy (for example from eating too little or exercising a lot), thyroid problems, raised prolactin or PMOS can disturb this signal. Then no follicle fully matures, or the LH surge that triggers ovulation does not come.

And as mentioned before: unfortunately, a period is not a reliable sign that ovulation has taken place. Bleeding can start at some point even without ovulation. The lining was built up by estrogen and bleeds when estrogen levels fluctuate or drop, similar to the withdrawal bleed on the pill.

You may already know one common cause of missing ovulation: PMOS.

Side note: PMOS (formerly PCOS)

PMOS (formerly PCOS, polycystic ovary syndrome) is in short a syndrome in which there is a metabolic disorder and the female sex hormones get out of balance. As a result, the follicles in the ovary cannot mature properly and ovulation does not happen. The period is often missing or very irregular. Elevated androgens and insulin resistance often play a role.

To get the diagnosis from a doctor, at least two of the three Rotterdam criteria must be met and other causes ruled out:

• infrequent or missing ovulation, for example long cycles or a missing period
• polycystic ovaries on ultrasound (in my view not a clear sign)
• elevated androgens, measured in the blood or visible, for example as acne or increased body hair

PMOS is often also called anovulatory androgen excess. An ultrasound is not enough to diagnose this complex hormonal disorder. Irregular periods can have many causes, and finding polycystic ovaries alone has no direct meaning.

Personally, I prefer the criteria of the Androgen Excess and PCOS Society, because they define PMOS by an excess of androgens. There is no single test for PMOS, because it is not a single disease but a group of symptoms. The criteria are met when all three of the following apply:

• Infrequent or missing ovulation and/or polycystic ovaries
• Androgen excess: visible (for example acne, increased body hair) and/or measurable in the blood
• Exclusion of other conditions that cause androgen excess

Phase 4: Autumn, oh autumn – the luteal phase

After all the beauty of the cycle’s summer, things get a little cooler again. In the luteal phase, progesterone reaches its peak. If you take ovulation as the dividing line, the second half of the cycle has now begun.

The remaining follicle turns into the so-called corpus luteum (yellow body). This empty follicle changes and produces progesterone, which is why progesterone is also called the corpus luteum hormone. Fitting, right?

While estrogen, LH and FSH level off, progesterone now takes center stage. Estrogen does rise slightly once more in the second half of the cycle, but progesterone clearly dominates.

Progesterone prepares the uterine lining so that a fertilized egg can implant. If no fertilization has taken place, the corpus luteum regresses after about 10 to 16 days and progesterone drops. The built-up lining is shed with menstruation in the cycle’s winter, and a new cycle begins.

In some women the second half of the cycle is clearly shortened, meaning shorter than about 10 days. Then either the whole cycle is quite short or the first half is comparatively long. As a result, the body lacks the so important progesterone. The most common cause of too little progesterone is missing or weak ovulation, because without ovulation no corpus luteum forms. Signs can include spotting before your period, mood swings, breast tenderness, headaches and cravings.

More man than woman? Testosterone in the female cycle

Okay, that’s exaggerated. But did you know that testosterone, often called the “male sex hormone”, also dominates in women most of the time? Measured in absolute amounts, testosterone in the blood is higher than estradiol most of the time. Only shortly before ovulation and in the middle of the luteal phase are both similarly high.

But why? In women, testosterone is mainly important for producing estradiol: the enzyme aromatase converts testosterone into estradiol. Aromatase activity is high mainly in the ovaries, but also in fat tissue, breast tissue, bone and the brain.

The adrenal glands play a central role here. Among other things, they produce adrenaline and noradrenaline, the stress hormone cortisol, aldosterone and DHEA, a precursor of testosterone.

What happens under stress

With psychological-emotional and physical stress, the body needs more cortisol to put out the “fires”. Cortisol is basically the fire brigade that contains the stress in the body.

Chronic stress acts on the brain via the stress axis and can dampen the signals to the ovaries. As a result, ovulation comes late, is weaker or does not happen at all. Without ovulation no corpus luteum forms to produce progesterone, so there can be too little progesterone relative to estrogen. The often-quoted idea that the body diverts progesterone directly into cortisol (“progesterone steal”), on the other hand, is not scientifically proven.

Stress is often a big factor in hormonal imbalances and cycle problems, and not rarely in an unfulfilled wish for a child. That is where I come in, ideally before the stress takes over and your hormone system gets out of balance.

Personal words to finish

For a long time, everything around women’s health, especially the cycle and menstruation, was full of shame. Education about what happens in the female body practically did not exist, at least when I was at school.

That is why I hope I could bring the processes of the cycle closer to you, better than the biology teacher at school or parents who are often a bit overwhelmed by it themselves. My goal: your life in your (hormonal) center.

I know eating disorders, period loss and hormone chaos from my own experience. You too deserve to live a self-determined life, and I would love to support you with that.

Feel free to tell me on Instagram which phase of the cycle has puzzled you the most so far.