Your menstrual cycle: phases, symptoms and duration

Your fifth vital sign

What is the menstrual cycle?

The menstrual cycle is our fifth vital sign and a fundamental indicator of reproductive health¹. It comprises a series of physical and hormonal changes in the body that repeat monthly and prepare your body for a possible pregnancy.

Knowing about this exciting process is crucial to boosting your:

reproductive health
family planning
overall health care

In this article, we will provide you with an in-depth insight into the menstrual cycle as a fascinating phenomenon of the female body.

We want to help you understand and appreciate this complex but vital biological process of your body.

The four main phases of your cycle

What are the different phases of the menstrual cycle?

The menstrual cycle has two main phases: the follicular phase and the luteal phase.

To make the cycle even easier to visualize, it is often divided into four main phases. This breakdown takes into account not only hormonal changes but also the physical and emotional experiences that many women go through:

Menstrual phase
Follicular phase
Ovulatory phase
Luteal phase

Each of these phases is characterized by specific hormonal changes and physical adjustments that can affect you both physically and emotionally.

How long does the cycle last on average?

The average cycle length is around 21–35 days, but can vary from woman to woman⁴. You don't need to worry about fluctuations of up to 7 days, but larger deviations should be clarified by a doctor⁴.

To calculate the length of your cycle, note the period from the first day of your period to the day before the start of your next period. This understanding of your individual cycle length provides you with valuable insights into your body.

The start of your Cycle

1. Menstruation

Marks the first day of your cycle
Lasts approximately 3–7 days
Your body sheds the uterine lining
Often accompanied by menstrual pain and cramps for many women

The menstrual phase marks day 1, i.e. the start of your cycle. If no fertilization has taken place in your previous cycle, the body breaks down the lining of the uterus. This leads to menstrual bleeding, also known as a period.

This phase usually lasts between 3 and 7 days, and for many women is accompanied by menstrual pain, cramps and other premenstrual symptoms.

PMS: When we don’t feel right before our period

Many women experience what is known as premenstrual syndrome (PMS) in the days leading up to their period. These symptoms usually begin a few days before menstruation starts and often subside with the onset of bleeding. The symptoms can vary widely but commonly include:

Tender breasts
Mood swings
Irritability
Low libido
Fatigue
Bloating
Back pain

Please remember: extreme period pain is not normal and should be checked by a medical professional.

Your period typically lasts between three and seven days. However, this time frame can vary from cycle to cycle and depends on various factors such as age, hormonal fluctuations, diet, stress and physical activity.

The average amount of period blood is around 30 to 40 ml, roughly equivalent to the contents of a small espresso cup. Quantities up to 80 ml are generally considered normal².

Some menstruating women experience particularly heavy bleeding or other cycle disorders. Bleeding that is very heavy or unusually prolonged is medically referred to as menorrhagia (blood loss over 80 ml)².

If your period stops even though you're not pregnant, breastfeeding, or going through menopause, this is referred to as amenorrhea. Infrequent periods, where the interval between menstruation consistently exceeds 35 days, are known as oligomenorrhea.

Menstrual irregularities can be caused by various factors such as hormonal imbalances, extreme weight loss or gain, stress, and chronic illnesses.

Growth of your follicles

2. The Follicular Phase

Release of follicle-stimulating hormone (FSH)
Follicles grow and mature
Estrogen production increases
Uterine lining begins to build up
Ends with ovulation

The follicular phase begins after menstruation. The duration of the follicular phase can vary from person to person, but is typically between 10 and 14 days⁴.

During the follicular phase, the brain, or more precisely the pituitary gland, stimulates the release of follicle-stimulating hormone (FSH). This hormone promotes the growth and maturation of the follicles in the ovaries. Follicles are cavities that each contain an egg cell.

The hormone oestrogen is produced in the walls of these follicles. As the follicles mature, the oestrogen level rises steadily. As a result, the lining of the uterus is rebuilt, better supplied with blood and more nutrients.

During this process, one of the follicles becomes dominant and matures to its largest size.

The follicular phase ends with the onset of ovulation and the transition to the next phase of the menstrual cycle, the ovulation phase.

Ovulation

3. The Ovulation Phase & Ovulation

Begins after the follicular phase
Lasts around 16–32 hours
Rise in luteinizing hormone (LH)
Dominant follicle ruptures and releases the egg

The ovulation phase is the shortest phase of the menstrual cycle. It only lasts around sixteen to 32 hours⁴ and begins with a rise in luteinizing hormone (LH). The luteinizing hormone is released in response to the signal from the pituitary gland, following the previously increased oestrogen level.

The luteinizing hormone triggers ovulation by causing the dominant follicle (egg follicle) to burst and release the egg into the fallopian tube.

Your ovulation usually occurs around the middle of your menstrual cycle, i.e. around day 14 in an average cycle of 28 days. However, the exact time of ovulation varies from woman to woman and even from cycle to cycle.

More specifically, you ovulate around 10 to 12 hours after the LH hormone surge⁴. This time marks the peak of your fertility in the cycle.

There are various methods to recognize your ovulation. Some women feel physical signs such as mittelschmerz, a slight twinge in the lower abdomen, which can indicate ovulation. In addition, cervical mucus or ovulation tests can also provide information about ovulation.

A particularly popular method is basal body temperature monitoring. Basal body temperature changes over the course of your cycle and rises shortly after ovulation.

Cycle computers such as Daysy offer you modern and convenient solutions for tracking your basal body temperature. Daysy shows you directly on the device with a red flashing light when your predicted ovulation occurs. You can also follow the development of your temperature curve in detail in the DaysyDay app. So you can always keep an eye on your ovulation.

Fertile days refer to the period in a woman's menstrual cycle when she is most likely to conceive and can best plan to get pregnant.

Although the most fertile time is marked by the time of ovulation, sexual intercourse can also lead to pregnancy a few days before you ovulate. The reason for this is that sperm can survive in a woman's body for up to 5 days³.

Your fertile window therefore begins five days before ovulation and ends the day after you ovulate. This results in a period of 6 days during which you are fertile³.

Knowing about the fertile window and ovulation is crucial for couples planning a pregnancy. This allows you to identify the most fertile days during your menstrual cycle and significantly increase your chances of successful conception.

Daysy offers an ideal solution for determining your fertile days. Daysy automatically signals your fertile days with a red light on the device.

After Ovulation

4. Luteal phase

Begins after ovulation
Lasts between 10 and 16 days
Progesterone production increases

The luteal phase, also known as the corpus luteum phase, begins directly after ovulation and lasts until the start of the next menstruation. This period lasts approximately 14 days, but can vary between 10 and 16 days⁴.

Compared to the follicular phase, the duration of the luteal phase remains fairly constant. A healthy luteal phase lasts at least 9 days⁴.

After ovulation, a temporary gland, also known as the corpus luteum, develops in the ovary from the empty follicle. This produces the hormone progesterone, which maintains the lining of the uterus for a possible pregnancy and prepares for implantation of the fertilized egg.

During this time, the egg travels through the fallopian tube to the uterus for around 5 days⁴.

If the egg is fertilized, it nests in the lining of the uterus about a week after fertilization, the corpus luteum remains intact and continues to produce progesterone⁴.

Daysy and Lady-Comp can indicate a potential pregnancy. You can recognize the prediction either in the DaysyDay app or directly on the Lady-Comp device. The devices recognize a potential pregnancy based on a constantly elevated basal body temperature that remains at a consistently high level of around 37° Celsius for more than 18 days.

If fertilization does not take place, the hormone level of progesterone drops again and the unfertilized egg is rejected. This leads to the uterine lining shedding and being excreted together with the egg during the subsequent period. This marks the start of your new menstrual cycle, and the cyclical miracle begins all over again.

Cycle & Health

What significance does the menstrual cycle have for women's health?

The importance of your menstrual cycle is not limited to fertility and well-being, but also serves as an important indicator of your general state of health. As the fifth vital sign, it provides important information about your health, similar to breathing or pulse¹. A regular and healthy cycle indicates normal hormonal regulation and production in your body.

If you notice any abnormalities, this can indicate possible hormonal imbalances or illnesses, such as Polyendocrine Metabolic Ovarian Syndrome (PMOS, formerly PCOS) or endometriosis.

These irregularities are initially no reason to panic, but recognizing them can help you to seek medical help at an early stage. Understanding your own cycle can therefore be crucial for the early detection and treatment of such conditions.

FAQs

How can you track your menstrual cycle phases?

You can track your cycle particularly easily using your basal body temperature. It is measured directly after waking up with a special basal thermometer or cycle computer, such as Daysy.

Within a cycle, the temperature fluctuations triggered by the hormones range from 0.2° to 0.45° degrees Celsius. You can then track these subtle changes with the DaysyDay app using the temperature curve.

Thanks to Daysy, you don't have to write anything down. You automatically receive practical information such as the duration of your cycle and the time of ovulation. This gives you exciting insights into your body and you always know exactly which phase of your menstrual cycle you are in.

What factors influence the menstrual cycle?

Just as diverse as the effects of the menstrual cycle on your body are the factors that can influence your cycle. They can range from small changes to your routine to external influences.

For example, your sleep-wake cycle, travel, shift work or stress can influence your body's physiological processes. Your body fat percentage also has a direct influence on your cycle.

Thanks to modern cycle computers, you can still track your cycle in all phases of your life. Daysy and Lady-Comp automatically adapt to your individual circumstances and reliably show you your fertile and non-fertile days.

What other effects does the menstrual cycle have on the body?

The menstrual cycle affects your body in various ways, both physically and psychologically. These influences can be triggered by hormonal changes during your cycle. You may experience the following effects during your cycle:

Water retention
Changes in skin and hair
Fluctuating energy levels and mood
Muscle strength and endurance
Increased or decreased sexual desire & libido
Change in consistency, quantity and appearance of cervical mucus
Influence on the immune response
Changes in digestion

In addition, many women experience a variety of symptoms on the days before their period, such as pain, breast tenderness, mood swings or even headaches. These symptoms are known as premenstrual syndrome and can have a major impact on women's everyday lives. The same applies here: if you notice severe PMS symptoms, it is advisable to seek medical advice.

So you can see how different the influences on your body can be. However, all the effects that occur are as different as we women ourselves. That's why it can be incredibly interesting to be able to assign these effects to your personal cycle phases.

Learn more

Discover all about PCOS: its symptoms, diagnosis, treatment options, and how tracking your cycle can support women living with this condition.

PCOS

Discover how measuring your basal body temperature can help you better understand your cycle and identify fertile and non-fertile days. With the basal body temperature method, you can make the most of your body for family planning and overall health.

Basal Body Temperature

Influencing Factors: What Can Affect Your Menstrual Cycle. Many factors like sleep, stress, weight, and environment can affect the menstrual cycle.

Factors Affecting Your Cycle

Sources

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Hallberg, L.; Högdahl, A. M.; Nilsson, L.; Rybo, G. Menstrual blood loss – a population study: variation at different ages and attempts to define normality. Acta Obstetricia et Gynecologica Scandinavica. 45(3), 320–351 (1966).

DOI: 10.3109/00016346609158455.

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Soumpasis, I.; Grace, B.; Johnson, S. Real-life insights on menstrual cycles and ovulation using big data. Human Reproduction. 2020(2). (2020).

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Speroff, L.; Fritz, M. A. Clinical Gynecologic Endocrinology and Infertility.

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Raith-Paula, E.; Frank-Herrmann, P.; Freundl, G.; Strowitzki, T. Natürliche Familienplanung heute: Modernes Zykluswissen für Beratung und Anwendung. Springer. 4. Auflage. (2008).

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Pehlivanoglu, B.; Balkanci, Z. D.; Ridvanagaoglu, A. Y.; Durmazlar, N.; Ozturk, G.; Erbas, D.; Okur, H. Impact of stress, gender and menstrual cycle on immune system: Possible role of nitric oxide. Archives of Physiology and Biochemistry. 109(4), 383–387 (2001, Oct).

Exploring your menstrual cycle: Phases, hormonal changes and the values for your health