What are the most dangerous days of menstrual cycles?

The egg released by the ovaries during the menstrual cycle has a lifespan ranging from a few hours to 2 days. 1 to 2 days during which you are fertile. 1 to 2 days which represent the most dangerous days of your menstrual cycle. So what are What are the most dangerous days when a woman's risk of getting pregnant is highest? When do they occur? Are they regular? Can you trust your body and your menstrual cycle to know your fertile days? We answer these questions together.

What are the most dangerous days to get pregnant depending on the length of the menstrual cycle?

If you are sexually active and do not want to get pregnant, it is always interesting to know your fertility window . However, we are all different, which is why it is important to take into account the length of cycles.

Although the The average length of a menstrual cycle is 28 days , this figure is only an average. The “normal” length of a menstrual cycle is therefore 24 to 32 days. In addition, some women may see their Menstrual cycles change due to different causes .

“Normal” menstrual cycle

A normal menstrual cycle is one that lasts between 24 and 32 days. Most menstrual cycle charts and models describe it as 28 days. In a 28-day menstrual cycle, the phases of the menstrual cycle are divided as follows:

• The menstrual phase from day 1 to 7
• The follicular phase from day 1 to 14
• The ovulatory phase / ovulation on day 14
• The luteal phase from day 14 to 28

The fertile days for a 28-day cycle are therefore:

• The 2 days following ovulation, i.e. from day 14 to day 16

The dangerous period for a cycle lasting 28 days , days during which sexual intercourse with penetration and vaginal ejaculation should be avoided are:

• The 5 days preceding ovulation, i.e. from day 9 to day 14
• The 2 days following ovulation, i.e. from day 14 to day 16

Short menstrual cycle

The menstrual cycle is said to be “short” when it lasts less than 24 days. It is considered irregular/abnormal when it lasts less than 21 days over a period of more than 6 months: because the length of the cycle can be a sign of a health problem, it may be worth consulting a health professional to check that everything is okay.

In a short cycle, the follicular phase is shorter, while the luteal phase is similar to that of a normal cycle. So, if your menstrual cycle lasts 22 days, the phases of the menstrual cycle are distributed as follows:

• The menstrual phase from day 1 to 7
• The follicular phase from day 1 to 8
• The ovulatory phase / ovulation on day 8
• The luteal phase from day 8 to 22 (the luteal phase always takes 14 days, the calculation is obtained by subtracting 14 from 22).

The fertile days for a 22-day cycle are therefore:

• The 2 days following ovulation, i.e. from day 8 to day 10

The dangerous days for a short menstrual cycle of 22 days , days during which sexual intercourse with penetration and vaginal ejaculation should be avoided, are:

• The 5 days preceding ovulation, i.e. from day 3 to day 8
• The 2 days following ovulation, i.e. from day 8 to day 10

Long menstrual cycle

The menstrual cycle is said to be “long” when it lasts longer than 32 days. It is considered abnormal when it lasts longer than 38 days over a period of more than 6 months. Since cycle length can be a symptom of a health issue, such as polycystic ovarian syndrome (PCOS), we recommend consulting a healthcare professional to check that everything is okay if your cycle exceeds this length.

In a long cycle, the follicular phase is longer and ovulation is later, while the luteal phase is similar to that of a normal cycle (14 days). So, if your menstrual cycle lasts 34 days, the phases of the menstrual cycle are distributed as follows:

• The menstrual phase from day 1 to 7
• The follicular phase from day 1 to 20
• The ovulatory phase / ovulation on day 20
• The luteal phase from day 20 to 34 (the luteal phase always takes 14 days, the calculation is obtained by subtracting 14 from 32).

The fertile days for a 32-day cycle are therefore:

• The 2 days following ovulation, i.e. from day 20 to day 22

Dangerous days for a long menstrual cycle lasting 32 days are :

• The 5 days preceding ovulation, i.e. from day 15 to day 20
• The 2 days following ovulation, i.e. from day 20 to day 22

The Importance of Understanding the 4 Phases of the Menstrual Cycle

To understand and anticipate the most dangerous days of your menstrual cycle, it is necessary to understand how it works. The menstrual cycle is a finely orchestrated biological process that takes place each month in the bodies of women and all menstruating people. It occurs in four phases .

The menstrual phase

The menstrual phase begins when the endometrium, or the inner lining of the uterus, sheds and is expelled from the body: this is menstruation . This phase, which generally lasts 3 to 7 days, marks the beginning of the menstrual cycle. It is often associated with symptoms such as abdominal cramps, bloating, and mood swings. This phase is not considered dangerous from a fertility perspective .

The follicular phase

The follicular phase begins on the first day of menstruation and lasts until ovulation. Under the influence of the FSH hormone, several follicles grow in the ovaries, although only one usually matures. This phase is characterized by a gradual increase in energy, a stable mood, and a gradual increase in libido. From a fertility perspective, it is considered safe since no egg has yet been released .

The ovulatory phase / Ovulation

Ovulation is the phase during which the follicle releases a mature egg in response to a surge in the LH hormone. This short period represents the peak fertility period for women—these are the dangerous days when the newly released egg travels down the fallopian tubes. Some women may notice clear, stringy cervical mucus and experience mild ovulatory pain, such as mild abdominal cramping.

The luteal phase

Following ovulation, the empty follicle transforms into a corpus luteum, producing primarily progesterone to prepare the uterus for implantation of the fertilized egg, if necessary. If the egg is not fertilized, the corpus luteum disintegrates, causing a drop in hormones and the onset of menstruation. During this phase, premenstrual symptoms such as breast tenderness, fatigue, or mood swings may occur.

And the fertility window

To determine which days are dangerous, it's important to understand the fertile window. This is the time when the egg released by your ovaries travels through the fallopian tubes at its peak health to implant in your uterus.

What is the fertility window?

The fertile window is the 24- to 48-hour period following the release of a mature egg from the ovary. The egg is then ready to be fertilized and travels through the fallopian tubes toward the uterus. The entire body is then ready for fertilization: the vagina secretes a slippery, whitish discharge, which facilitates access for sperm, and the walls of the uterus become covered with endometrium to better accommodate the fertilized egg.

Which days of the menstrual cycle fall within the fertile window?

The days of the menstrual cycle that correspond to the fertile window are the days following the ovulation phase. In an average cycle (i.e., 28 days), these days correspond to days 14 to 16 of the menstrual cycle.

That being said, sexual intercourse should not be avoided during this period only. In fact, the lifespan of sperm varies between 2 and 5 days in the female genital tract . Thus, the oocyte can be fertilized by a sperm released up to 5 days before ovulation. It will therefore be necessary to avoid sexual intercourse with penetration and vaginal ejaculation 5 days before the fertility window: from day 9 to day 16.

The importance of egg and sperm lifespan

Once the egg is released from the ovary, it travels into the fallopian tube where it can survive for 12 to 48 hours. The survival time of sperm in the female reproductive system varies from 2 to 5 days, but their optimal mobility period is 48 to 72 hours. Post-ovulatory mucus destroys sperm within 2 to 3 hours.

As explained above, it is essential to take the lifespan of sperm into account. In fact, the newly released egg can be fertilized by a sperm from sexual intercourse that took place up to 5 days before ovulation.

How to calculate your menstrual cycle to avoid getting pregnant?

As you will have understood, the fertility of menstruating people is therefore linked to ovulation: it is essential not to have unprotected vaginal intercourse in the 5 days preceding ovulation and in the 2 days following it. This is why knowing how to identify ovulation in your cycle is interesting.

Start by knowing your cycle

To detect your ovulation , the first step is to know the length of your menstrual cycle. As we have seen, ovulation varies depending on the length of your cycle. Start by calculating your cycle, which will allow you tocalculate your ovulation period and therefore have a better idea of your ovulatory phase.

To do this, there are three steps:

1. Identify the start of your menstrual cycle – it begins on the first day of your period
2. Count the days from this first day until the occurrence of a new cycle (this will be marked by the return of your period). To count, you can use your calendar by marking the date of your period and/or use a period and cycle tracking app.
3. Repeat this process at least 3 times: menstrual cycles can vary enormously in their duration, which is why it is useful to count the duration of your cycles over several consecutive cycles. This will be all the more important since the occurrence of the ovulatory phase depends on the duration of the menstrual cycle.

Once you know the length of your menstrual cycle and whether, and only if, it is regular in duration, you can estimate without too much error which days in your menstrual cycle are dangerous.

Your body is sending you signs, learn to detect them

Beyond tracking the length of your menstrual cycle, there are physical signs that can let you know you are ovulating and therefore particularly fertile.

Cervical mucus

Around the time of ovulation, cervical mucus (the vaginal discharge) becomes clearer, stretchy, and stringy, resembling the texture of egg white. This change in your mucus helps sperm move more easily through the cervix.

Basal temperature

After ovulation, it is common to see a slight increase in basal body temperature (BBT). By measuring BBT each morning, many women can detect this small rise, indicating that ovulation has occurred. To easily measure your body temperature, you can use a basal body temperature thermometer to detect ovulation .

You can record your temperature and cervical mucus in a menstrual diary specifically designed for this purpose. This will allow you to easily identify your fertile window and the dangerous days of your cycle if you do not want to get pregnant.

Monitoring your cycle by tracking your temperature and observing your cervical mucus is called symptothermal method. To learn more about symptothermal method, read our article Symptothermal Method: A Great Tool for Understanding Your Cycle to learn everything about your cycle.

Ovulation pain

Some menstruating people experience a sharp, stabbing pain on one side of their abdomen, commonly referred to as “ovulatory pain,” “mid-cycle pain,” or “mittelschmerz.” This pain may indicate the release of the egg from the follicle.

Natural solutions like Miyé's soothing pain-relieving serum can help you reduce this sensation, or Gyneika's menstrual pain relief food supplements .

For some women, the pain during ovulation can be very intense. In this case, we recommend using the Bluetens electrostimulation device , which will cut off the pain signal!

Afraid of making mistakes? Use dedicated tools

Whether your cycle is too irregular to track this way or the physical signs don't seem so easy to follow, there are tools you can use to help you better track and understand your body.

Ovulation tests

Available in pharmacies, ovulation tests measure the concentration of luteinizing hormone (LH) in the urine. A surge in LH typically precedes ovulation by 24 to 36 hours. These tests are marketed primarily to women planning a baby, but you can use them to better understand your body; however, they may be expensive for contraceptive use.

Symptothermal method

We were just talking about symptothermal method above, which is the study of the menstrual cycle by monitoring and interpreting two parameters: basal temperature (resting body temperature) and cervical mucus .

With proper training (and yes, it's best to be accompanied by a professional in this learning process) and rigorous practice (you have to do this monitoring every day), symptothermal method is one of the most effective contraceptives. And what's more, this method is 100% natural. We tell you EVERYTHING about symptothermal method in the article Symptothermal method, a great tool for deciphering your cycle.

Mobile applications

Many apps for tracking menstrual cycles use algorithms to predict ovulation based on user-provided data, such as cycle length, basal temperature, and other symptoms. They also have the added benefit of telling you the dangerous days of your cycle (those times around ovulation when you may be fertile). What's more, because they're on your phone, you have them with you at all times (unlike a paper-based tracking calendar). Be careful, however, if you have an irregular cycle, as the algorithm in these apps is often very limited and sometimes offers a fairly rough estimate, especially if your cycle is always the same length.

Beware the myth of “safe days”

This article wouldn't be 100% relevant if we didn't take the time to debunk the myth of safe days. There are supposedly dangerous days (those surrounding ovulation) and safe days, during which you can have vaginal intercourse without fear. In theory, this myth of "safe days" is real. But not in practice.

In practice, thousands of factors can come into play...

• Your menstrual cycle can be disrupted for a month and become longer for many reasons: stress, weight gain or loss, travel, etc. Because the length of your cycle changes, so does your ovulation date, and the dangerous and safe days change;
• You can release two eggs , at the same time, or at different times: it happens that two eggs are released by your ovaries. In this case, it is difficult to know exactly when you are fertile or not;
• Your egg may live a little longer than the supposed 48 hours;
• Your partner's sperm may live a little longer than the expected 2 to 5 days;
• You know when you ovulate, of course... but since sperm have a lifespan of 5 days, you must therefore stop vaginal intercourse with ejaculation 5 days before ovulation to avoid any risk: detecting your ovulation is therefore not enough ...

In other words, if the myth of “safe days” is a reality (as a menstruating person you are not fertile on a daily basis) BUT cycles can be so fragile and so changeable that calculating your “dangerous days” is not enough to avoid pregnancy . If you want to use this method as a means of contraception, it will be interesting to combine it with other tools to avoid any risk.

To avoid pregnancy, remember to choose a suitable contraceptive method

Generally speaking, if you're looking to avoid pregnancy, it's best to adopt a contraceptive method that's right for you. Finding the right one for you isn't easy: all methods have their pros and cons, and their practicality will depend on your criteria. Here's a list of contraceptive methods to add to your ovulation tracking and cycle-risk days to prevent pregnancy.

Hormonal contraceptive methods

Hormonal contraceptive methods for menstruating people are popular options for preventing pregnancy. They work by altering hormone levels in the body and simulating pregnancy to prevent further pregnancy. They are effective and widely used.

• Oral contraceptive pills: These pills contain synthetic hormones, usually a combination of estrogen and progesterone or progesterone alone. They work by preventing ovulation, thickening cervical mucus to prevent sperm from reaching the egg, and changing the uterine lining to prevent implantation of the fertilized egg. An alternative is the progestin-only pill, which is a birth control pill containing only progesterone. It is often recommended for women who cannot use estrogen;
• Contraceptive patch: This is a thin, adhesive patch containing hormones that is applied to the skin. It continuously releases hormones through the skin to prevent ovulation;
• Vaginal ring: This is a soft, flexible ring that is inserted into the vagina. It continuously releases hormones to prevent ovulation and act on the cervical mucus and uterine lining;
• Contraceptive injection: This is an intramuscular injection that releases contraceptive hormones into the body. A single injection can provide contraceptive protection for several weeks or months;
• Contraceptive implant: This is a small, flexible rod inserted under the skin of the arm. It slowly releases contraceptive hormones into the body over several years.

These hormonal contraceptive methods are very effective when used correctly. However, they can have potential side effects and do not protect against sexually transmitted infections (STIs).

We recommend that you consult a healthcare professional to discuss your contraceptive options and determine the method best suited to your needs and medical situation.

Non-hormonal contraceptive methods

Non-hormonal contraceptive methods offer alternative options to prevent pregnancy without resorting to synthetic hormones. While some are particularly effective, others, such as ovulation tracking, are less reliable.

• Male condom: The male condom is a latex or polyurethane barrier that is placed over the penis before sexual intercourse to prevent direct contact between semen and the vagina. It is the only method of contraception that also has the advantage of protecting against sexually transmitted diseases (STDs);
• Female condom: The female condom is a polyurethane or nitrile sheath that is inserted into the vagina before intercourse to prevent contact between semen and the cervix. Unlike the male condom, it does not protect against STDs;
• Cycle tracking methods: This involves monitoring fertility signs, such as basal body temperature and cervical mucus consistency, to determine fertile days and avoid unprotected sex during this time. As discussed in this article, this method can be very reliable, however, it requires good training and being rigorous about monitoring your temperature and cervical mucus;
• Diaphragm: This is a small silicone or latex dome that is inserted into the vagina to cover the cervix and prevent sperm from reaching the uterus;
• Contraceptive sponge: This is a sponge impregnated with spermicide that is inserted into the vagina before sexual intercourse to kill sperm;
• Copper IUD: The copper IUD is a small T-shaped device inserted into the uterus. Copper creates a toxic environment for sperm, preventing fertilization;
• Fallopian tube ligation : If you do not want to become pregnant, tubal ligation is a surgical procedure that closes the fallopian tubes and thus blocks the arrival of eggs in your uterus. It is irreversible and can be difficult to obtain from doctors who do not always want to perform it, especially on young and childless women;
• Breastfeeding method (lactational amenorrhea method): This method is based on the fact that exclusive breastfeeding can suppress ovulation for a period of time, thus acting as a form of contraception. However, its effectiveness depends on how it is practiced. As the period around the return of menstruation is particularly fertile, do not hesitate to speak to your midwife or gynecologist before choosing it;
• Withdrawal: The withdrawal method involves removing the penis from the vagina before ejaculation to prevent sperm from entering the uterus. However, it is considered one of the least reliable contraceptive methods. This is because some semen may leak from your partner's penis during penetration.

Non-hormonal contraceptive methods can vary in effectiveness and convenience. The choice of method depends on your personal preferences, medical situation, and contraceptive needs. We recommend consulting a healthcare professional for information on the method best suited to your situation.

Contraceptive methods for the partner

Recently, research has also focused on contraceptive methods for men in order to involve them in this process. We inevitably think of the male condom here, but it is no longer the only alternative. While the male pill is still in the testing phase, heated briefs and heating rings are now recognized contraceptive methods.

• Heating briefs: This method relies on the fact that heat is spermicidal. Heating briefs keep the testicles against the body at a temperature of over 37°C. This has the effect of killing sperm and thus rendering the sperm infertile. It is necessary to wear the briefs for 15 hours straight each day to kill all the sperm. Tests must be carried out to verify that your partner's semen does not contain any sperm. Contact a healthcare professional to implement this method;
• Contraceptive rings for men: Like the heating briefs, this method relies on the fact that heat is spermicidal. However, the ring is less invasive than the heating briefs. The ring is placed around the penis and testicles and must also be worn 15 hours a day. Tests are required to verify that your partner's semen does not contain any sperm. Consult a healthcare professional to implement this method;
• Vasectomy: This is a surgical male sterilization procedure that aims to render a man incapable of producing fertile sperm and thus prevent fertilization. During a vasectomy, the vas deferens, the tubes that carry sperm from the testicles to the urethra, are cut, tied, or blocked. This operation is not always reversible, hence the reluctance of some doctors to perform it: seek advice from a healthcare professional .

The dangerous days of the menstrual cycle correspond to your fertile period.

If you do not want to get pregnant, these are the days during which you should not have sexual intercourse with penetration and vaginal ejaculation. They correspond to 5 days before the ovulatory phase until the 2 days of the ovulatory phase, or 7 days in total. However, because the length of menstrual cycles can change and vary from one month to the next for various reasons, the contraceptive method of following your cycle without strict training and monitoring is not 100% reliable. If you do not want to get pregnant, it will therefore be interesting to possibly combine it with another method of contraception.