Menstruation: Understanding the menstrual cycle

Menstruation: Understanding the menstrual cycle

Since the dawn of time, menstruation has been shrouded in a veil of mystery and surrounded by many myths. Let’s shed light on this natural and normal process.

The female reproductive system – a few basic definitions

Vagina

A canal 8 to 10 cm long made of elastic folds leading from the cervix to the vulva and used for copulation (sexual intercourse).

Vulva

The external female genitals.

Uterine cervix

Lower part of the uterus that extends from the uterus to the vagina.

Uterus

A hollow, pear-shaped muscular organ where the fertilized egg is held. This is the organ in which the fetus develops during pregnancy.

Fallopian tubes

Tubes lined with small, hair-like projections called cilia leading from the ovaries to the uterus. This is where the sperm meets the egg during fertilization. 

Ovaries

Almond-shaped reproductive glands located at the end of each Fallopian tube, which produce the eggs and secrete sex hormones (e.g. estrogen).

Corpus luteum

A temporary, progesterone-secreting structure in the ovary that develops from an ovarian follicle after the release of a mature egg to the Fallopian tubes.

Ovum

The female egg produced by the ovaries.

Endometrium

The mucus membrane that lines the uterus and provides a rich, nourishing environment for the fertilized egg.

Estrogen

A hormone secreted by the ovaries to stimulate the activity of the Fallopian tubes, among other things.

Progesterone

A hormone secreted by the ovaries that, among other things, regulates the uterine lining during pregnancy. 
 

The onset of menstruation

Each month, from puberty to menopause, the female reproductive system, especially the uterus, prepares for pregnancy. With the onset of menstruation, pregnancy becomes possible following unprotected sexual intercourse.

Start of menstruation: Between 9 and 18 years of age (on average around 12 or 13)
End of menstruation: Between 45 and 55. 

The menstrual cycle

On average, the body produces one egg every 28 days. Again, since all women are different, some will have longer cycles and others shorter ones.

Menstrual cycle
- Start of cycle (Day 1): first day of bleeding
- Average length of bleeding: 3 to 6 days
- End of cycle: Last day before Day 1 (around day 28)


From menstruation to ovulation

When fertilization does not occur, the endometrium and ovum are shed by the uterus through the menstrual blood. At this point of the cycle, the quantity of estrogen and progesterone is at its lowest level. Toward the end of menstruation, a new ovum begins to grow in one of the ovarian follicles. The level of estrogen gradually increases, causing the endometrium to thicken. The follicle also continues to grow until ovulation occurs.

Ovulation

Ovulation occurs when the mature follicle ruptures and, in turn, discharges the ovum from the ovary. This small cell released from the reproductive gland slowly travels toward the Fallopian tube. It is during this part of the process that fertilization can occur. At this precise moment, the level of estrogen reaches its peak. Moreover, the endometrium continues to thicken under the influence of the progesterone secreted by the ruptured follicle, called the corpus luteum. The glands located in the uterine cervix then produce a clear, slippery mucus that helps the sperm reach the uterus during sexual intercourse. (Some women can determine when they are ovulating through changes in these vaginal secretions).

From ovulation to the end of the cycle

This phase, which extends from ovulation to the last day before menstruation, never changes. It always lasts 14 days.

If fertilization has occurred, the increased levels of estrogen and progesterone will lead to other changes in the endometrium that will enable the fertilized egg to develop in the uterus.

If the egg has not been fertilized, the corpus luteum will break down and the secretion of hormones will abruptly cease. The endometrium then weakens and deteriorates, giving way to menstruation and the start of a new cycle.

The fertility period

The ovum has a lifespan of approximately 24 hours. The sperm can survive up to 5 days in the female reproductive organs. Consequently, fertility starts 5 to 6 days before ovulation and ends 2 to 3 days after. In fact, natural methods of birth control rely on this principle to achieve or avoid pregnancy.

Pharmacy services

Do you have questions about menstruation, pregnancy, contraception, premenstrual syndrome (PMS) or other related issues? Talk to your pharmacist. He’s there to help!

In addition, Uniprix offers a range of professional pharmacy services to assist you:

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