Long menstrual cycle: why does it last longer?

The average menstrual cycle lasts 28 days. But its length can vary from one woman to another, and even according to the different phases of a person's life. The 28-day average for a menstrual cycle is, as said, only an average; some women have a much longer cycle.

What is a menstrual cycle?

The menstrual cycle is made up of four phases. The first is menstruation. This is the first part of the female cycle. During this period, which lasts an average of 4 to 7 days depending on the woman, the uterine lining (the endometrium) disintegrates. It is evacuated in the form of bleeding, through the vagina if fertilization has not taken place.

After menstruation comes the follicular phase. This is when the body prepares for a possible pregnancy. Under the action of estrogen, the endometrium gradually fills with blood, swelling and becoming ready for implantation.

Then the hormone LH comes into play, triggering ovulation, corresponding to the third phase of the menstrual cycle. This hormone opens the ovarian follicle, releasing the egg. The egg then descends through the Fallopian tube to nestle in the uterus. The journey generally takes 3 to 4 days, and the egg remains in the uterus for 1 day before it begins to disintegrate. During these 5 days or so, the egg can be fertilized by a sperm. This is known as the window of fertility. We tend to say that ovulation takes place on the fourteenth day of the cycle, but this varies from woman to woman. Some women ovulate later than this.

After ovulation comes the luteal phase. During this period, the ovarian follicle transforms into thecorpus luteum. This corpus luteum releases estrogen and progesterone into the bloodstream. This prepares the endometrium to receive a fertilized egg, andaccompanies the development of nidation until the baby is born. If, on the other hand, fertilization does not occur, the ovum decomposes and is evacuated. The luteal phase always lasts 14 days, unlike the follicular phase, which can vary in length.

Why is it called a long menstrual cycle?

A menstrual cycle is considered long when it lasts more than 35 days. If your cycle lasts 40, 45 or even more days, then it's considered a long menstrual cycle.

In reality, it's only the follicular phase, the period before ovulation, that's longer than average. If you have a long menstrual cycle, this means that your body takes longer to make an egg, and that ovulation will not actually take place untilafter the 14 days indicated on average.

However long your cycle lasts, the luteal phase always lasts 14 days.

How long does a menstrual cycle usually last?

The length of a menstrual cycle is calculated from the 1st day of menstruation to the day before the next first day of menstruation. Some women also have irregular cycles, meaning that the duration will vary from one cycle to the next.

A long cycle lasts more than 35 days, while a short cycle lasts less than 21 days. You can use a period app to calculate the length of your cycle, and thus determine your menstrual calendar ! This will help you avoid unexpected bleeding!

What causes a long menstrual cycle?

Long menstrual cycles can have a number of causes:

Hormonal changes

Hormonal changes, such as those associated with taking or stopping hormonal contraceptives like the contraceptive pill or the hormonal IUD. When you stop using this type of contraception, it can take several months for your cycle to regulate itself and return to normal.

Age and the onset of menopause, with all its associated hormonal imbalances can also lead to longer or more irregular cycles.

Environmental and lifestyle factors

Your environment and lifestyle also play a considerable role in the length of your cycles. A stressful period or chronic stress during your periodAnxiety, depression, major change or psychological disorders can all lead to menstrual disorders of varying degrees. It's therefore possible to see the length of your cycle lengthen when you're subject to these types of factors.

Lifestyle also plays a role in cycle length. For example, excessive or intense exercise will reduce estrogen levels. The production of this sex hormone is directly linked to body fat, so if you lose weight (body fat), estrogen production can tend to drop, leading to longer, more irregular cycles and sometimes even an absence of menstruation (also known as secondary amenorrhea).

Of course, this doesn't mean you should stop practising sport!


Finally, certain diseases or disorders can cause longer cycles. Such is the case with polycystic ovary syndrome (PCOS): this hormonal disorder is very common, affecting around 10% of women, or one in 10 of childbearing age. In fact, it's the leading cause of female infertility. It is characterized by very high levels of the hormone testosterone. Symptoms include acne, weight gain, hirsutism (abnormally high hair growth) and irregular cycles (which are often abnormally long).

Thyroid dysfunction can also be a source of irregular and/or abnormally long cycles. Indeed, if the thyroid is dysfunctional, the production of sex hormones can also be affected, delaying ovulation.

What are the effects of a long menstrual cycle on the body?

A long menstrual cycle can have a number of different effects on your body.

Irregular periods

It's possible for a cycle to last a long time without being irregular. Your cycles can sometimes be long, sometimes shorter. Irregular cycles are those that vary in length from month to month. When you have irregular cycles, it's more difficult to know when you're ovulating, and therefore to have irregular periods.

Impact on fertility

Long cycles do have an impact on fertility. When you have long cycles, you ovulate less often. So, statistically, it can be more difficult for some women to conceive a child. But some studies show that women with long cycles ovulate less often, but have better quality oocytes. So fertility rates are not lower in women with longer menstrual cycles.

How to treat a long menstrual cycle?

In the event of a long menstrual cycle, or a sudden change in your menstrual cycle and its length, you should consult a healthcare professional (doctor, midwife or gynecologist). He or she can help you find the cause of this ovulation disorder or delay by carrying out a number of tests (ultrasound scan, hormone test, etc.).

Sometimes, long cycles are also naturally like this: it's by carrying out various tests that your health professional will be able to find out whether your cycle problems stem from a pathological or natural cause.

Long menstrual cycle FAQ

Is it possible to have a 45-day menstrual cycle?

Some women can have a 45-day cycle. The follicular phase will then be longer than average.

Is it possible to have a long menstrual cycle of 60 days?

It is possible for some women to have a 60-day menstrual cycle. The luteal phase always lasts 14 days, but ovulation is delayed in this case.

Is it serious to have a long menstrual cycle?

The cause of a long menstrual cycle can only be determined by an examination with a health professional: the causes may be pathological, such as hormonal imbalance, PCOS, or psychological. But a cycle can also be long naturally, without any pathological causes.

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