Almost 40 years pass between the first menstrual bleeding and menopause. Every month, the female body prepares itself for the eventuality of pregnancy. On average, the cycle lasts 28 days. However, the female body is not a machine, and both a duration of 21 days and 35 days are normal. For most women, the cycle also fluctuates within these limits over the years.
The ups and downs of hormones
“Proliferation or build-up phase: Under the influence of the hormone FSH, several follicles begin to mature in the ovary. As a rule, one follicle soon becomes established and continues to grow as the only one. The maturing follicle produces more and more estrogen. The female hormone ensures that the lining of the uterus grows.
The mature egg is now capable of fertilization for about 24 hours.
“Secretion or corpus luteum phase: After ovulation, the empty follicle remains in the ovary. This so-called corpus luteum now switches hormone production and secretes more progesterone. This messenger substance prepares the uterus for a fertilized egg: Nutrients are deposited in the mucous membrane. At the same time, estrogen levels in the body drop.
“Menstruation: The excess tissue from the uterus is shed during menstrual bleeding.
The first day of menstruation is also the first day of the new cycle: follicles mature again, and the uterine lining rebuilds under the influence of rising estrogen levels. The purpose of menstruation is therefore to shed the old uterine lining and make room for a new lining that will make pregnancy possible again in the next cycle.
Hormonal contraceptives switch off the natural cycle. Because the body is supplied with sex hormones from outside, it stops producing its own messenger substances. The ovaries are “paralyzed,” and the eggs and endometrium no longer mature.
Estrogens – 21 + 7 days
Progestogens – 28 days
Progestin-based contraceptives (new mini-pill, mini-pill, contraceptive sticks, three-month injection) reduce the activity of the endometrium. Since no estrogen is added (as with the combined pill), the cyclic buildup of the mucosa does not occur. Bleeding becomes less frequent and weaker, and in some women there is no bleeding at all.
