Every woman goes through changes from girlhood to adolescence, and as a result, the body adapts until menarche (the first period) occurs. Menarche marks the beginning of a woman’s menstrual period, which is divided into three phases that last until menopause, when menstruation ceases and the body itself stops preparing for a potential pregnancy.
These three phases, which happen through hormonal changes, naturally repeat every month. When menstruation occurs, it can last about 3 to 7 days. The menstrual period considered normal lasts 28 days, but it is common for this period to vary between 23 and 35 days and be considered irregular. In the first years after menarche, it is very common for the menstrual period not to be properly regulated yet, and it may take an average of 3 years to regulate. This happens because the whole process depends on hormones produced in the ovaries, hypothalamus, and pituitary gland, and it may take some time until they function in a synchronized manner.
Some women may have an irregular menstrual period throughout their lives, which makes it difficult to become pregnant because it is hard to pinpoint their fertile window except by the signals that the body itself gives such as breast sensitivity and clear discharge compared to an egg white, which is a sign of ovulation. One way to regulate menstruation, and thus be sure of the days you will have your period, is by using birth control pills. This option is not suitable for those who want to become pregnant during this period, since the method inhibits ovulation.
Phases of the Menstrual Cycle
As mentioned above, the menstrual cycle occurs in three phases: the follicular phase, the ovulatory phase, and the luteal phase, with each performing its natural functions until the cycle is complete and everything starts over again. In the follicular phase, which begins on the first day of menstruation and lasts about 12 days on average, the hormone FSH increases, which stimulates follicles that, when mature, become eggs. The follicle, also known as “future egg,” is surrounded by cells responsible for hormone production, called granulosa. In this phase, there is a great stimulus in the production of these follicles until only one dominates, causing the others to stop functioning naturally.
In the ovulatory phase, the follicle that becomes dominant starts to produce high levels of estrogen, which induces the production of the hormone LH, the main one responsible for ovulation. This period lasts around 8 days, and its peak occurs on the 14th day (in the case of a 28-day menstrual cycle). During ovulation, the egg detaches and moves to the fallopian tube, where it waits to be fertilized by a sperm.
In the luteal phase, the granulosa cells that no longer contain an egg are then called the corpus luteum. This process lasts about 10 days on average. The corpus luteum is maintained through the production of the hormone LH, and the production of progesterone begins. With the start of this second hormone, LH production starts to drop its function, and about 14 days after ovulation, menstruation occurs.
To better understand the hormones and their functions during the menstrual cycle, let’s list each one and where it is located. For example, the hormone that releases gonadotropin, or GnRh, is produced by the hypothalamus, which is located in the brain. The follicle-stimulating hormone, also called FSH, is produced by the pituitary gland, which is also located in the brain, as is the hormone responsible for luteinizing, or LH, which is also produced by the pituitary gland. Lastly, estrogen and progesterone are produced by the ovaries.
See also: Why Does Menstrual Delay Happen?
Photo: clarissa rossarola
