Hvad er menstruation?

What is menstruation?

Have you ever wondered why you even have menstruation? This article explains the physiological changes that happen during a cycle, which causes the menstruation. Read on and get to know your body even better. 

Menstruation, also known as a period, is what happens when the outer lining of the uterus, known as the endometrium, is rejected or expelled. Besides the outer lining, the blood that is expelled also contains vaginal discharge, as well as proteins, minerals etc. But to really understand menstruation, you need to understand ovulation first. 

The time period between menstruation and ovulation 

The ovaries produce hormones which, amongst other things, regulates the uterus' activity. In the ovaries are the eggs, which rests in an ovarian follicle (a little bladder around the egg). In each cycle, one of the follicles will grow larger than the others and release an egg during ovulation. In rare cases 2 eggs will be released. 

In the period leading up to the ovulation, the lining of the uterus (endometrium) which was previously expelled will be built up again. Just before ovulation the lining is completely rebuilt.


During ovulation the follicle bursts, the egg is released and will live for an average of 12-24 hours. The egg travels from the fallopian tube towards the uterus.

The yellow body

After ovulation, a structure called the yellow body, or corpus luteum (latin for yellow body), will be formed. Corpus Luteum is a gland created in the ovaries. It creates hormones that thickens the lining of the uterus, which creates the possibility for an egg to attach itself. If you get pregnant, the corpus luteum will keep creating these hormones to avoid the maturing of more eggs in the ovaries. At some point the placenta will take over this hormone production. 

If the egg is not fertilized, the corpus luteum will break the egg down and dissolve it. When the egg is broken down, its production of hormones also stops. This drop in hormone level makes the surrounding blood vessels that supplies blood to the endometrium contract, which then "kills" the outer layer of the endometrium.  


After a little while the walls of these blood vessels will burst, which creates a bleed that also detaches the dead tissue of the endometrium. Subsequently the dead endometrium is expelled alongside the blood and vaginal discharge - this is what you know as your menstruation 

If you take contraceptive pills and pause for 7 days between each pack, the bleed you will experience is not like a "real" menstruation. Instead it is an artificially induced bleed, which happens because the hormone level maintained by the pills fall when you take the 7-day break. 

Finally, your menstruation is not just a menstruation, it's a reflection of how your body is doing. You can use each cycle to learn about your body, and maybe listen to what your body is trying to tell you.