The menstrual cycle is a chain of events that lasts from the first to the last menstruation (menarche) to the last menopause, characterized by menstrual bleeding, the purpose of which is the continuation of the lineage with reproduction and affects the whole body. When it comes to menstrual cycle or menstrual period, it is meant the period from the first day of a menstrual bleeding to the first day of the next. When the menstrual period is mentioned, the period with bleeding or the period without bleeding is not understood.
What is a normal cycle?
The normal cycle is every 21-35 days (28 days on average), bleeding lasts for 2-8 days and is characterized by 20-80 ml of bleeding. The menstrual cycle is a complex cycle controlled by the brain-ovaries-uterus system.
How many periods is the menstrual cycle divided into?
In order to understand this, it is necessary to first examine the events that occur in the body during the menstrual cycle.
Starting from the moment of adulthood, a hormone called GnRH is secreted from the hypothalamus region of the brain, which also stimulates the pituitary gland in the brain, from which hormones FSH and LH are secreted. These hormones mix with the blood at different times of the menstrual period with different oscillation patterns and start the development of egg cells by stimulating the ovaries. Again, with the effect of these and some other hormones, hormones called estrogen and progesterone are secreted from the ovaries. Estrogen secreted more than these two hormones causes the endometrium, which is the inner membrane of the uterus, to gradually thicken. Only 1 of the developing egg cells (follicle) reach full maturity and when the appropriate hormonal environment is formed, it cracks and ovulation occurs. This is called ovulation. After ovulation, more progesterone hormone begins to be secreted from the ovaries. Progesterone stops the thickening of the endometrium but allows it to mature. The egg cell discharged as a result of ovulation is captured by the tubas and begins its journey towards the uterus. Meanwhile, if fertilization occurs, the embryo formed attaches to the endometrium prepared by hormones and pregnancy occurs. If fertilization does not occur, the amount of hormones gradually decreases and as a result, when the level that protects the endometrium falls below the level that protects the endometrium, the thickened endometrium begins to shed with bleeding and is thrown out into the vagina. Later, this cycle continues until menopause, that is, until the egg cell is exhausted in the ovaries.
The part of the menstrual period up to ovulation is called the “follicular phase” as follicles develop in the ovaries or the “proliferative phase” because the endometrium thickens. The post-ovulation period is called the “luteal phase” or “secretory phase”.
What are the necessary conditions for menstruation?
• Hormone must be secreted from the brain
• Hormone must be secreted from the pituitary in response to hormones secreted from the brain.
• There should be follicles in the ovaries and these follicles should be able to secrete hormones.
• Endometrium must be present and sensitive to these hormones
• There should not be an anomaly that will prevent the emerging blood from flowing out.
How old is the first period?
It is not possible to know precisely at what age the first menstruation, which is the last stage of transition from childhood to adolescence, will occur. This may vary depending on breeds and environmental factors. The first menstruation in our country is generally between the ages of 11-14. If menstruation is not seen until the age of 16 and there are no symptoms such as enlargement of the breasts, inguinal and armpit hair growth, which are called secondary sex characters, it would be useful to contact a gynecologist. Some authors say that in cases where secondary sex characters develop, it can be expected until the age of 19 for the first menstruation. Cycles become irregular in the period after the first menstruation. In these cycles, there is usually no ovulation (anovulatory cycle). Sometimes bleeding occurs twice a month and sometimes every 3-4 months. These are all normal. It may take up to 2 years for menstruation and ovulation to settle.