The female reproductive system, unlike the male , undergoes regular cyclical changes. The menstrual cycle is a physiological process that occurs in women of childbearing age, during which the body prepares for a possible pregnancy every month. It begins on the first day of menstruation and ends the day before the start of the next menstruation. The menstrual cycle is generally considered to be 28 days long, and while this is the most common length, perfectly healthy women can have menstrual cycles of varying lengths. A normal cycle is considered to be a period from 21 to 35 days. But for ease of understanding, we will use a duration of 28 days. Traditionally, the first day of the menstrual cycle is considered to be the first day of heavy menstruation. Essentially, the menstrual cycle consists of two phases (follicular and luteal ), but we often talk about four phases, including ovulation.
Follicular phase
The first phase of the menstrual cycle is the follicular phase. The main hormone in this phase is estrogen, in particular 17-beta-estradiol. The main task of this phase is the growth of the inner uterine lining, the endometrium, which is preparing to receive a potentially fertilized egg. During this phase, several follicles mature in the ovaries until one becomes dominant. Duration: approximately 10–14 days (starts on the first day of menstruation and ends with ovulation).
What happens: Follicle-stimulating hormone (FSH) stimulates the ovaries to produce follicles. Each follicle contains one egg, and one of these follicles becomes dominant. Estrogen levels increase, which improves mood. Purpose: to prepare a mature egg for possible fertilization.
Ovulation phase
Ovulation usually occurs 14 days before the next menstrual period. At the end of the follicular phase, there is a so-called hormonal peak, detected by ovulation tests, during which FSH and LH stimulate the rupture of the mature follicle and release of the egg. Duration: 12-24 hours What happens: The surge in luteinizing hormone (LH) triggers the release of the mature egg, which travels from the ovary to the fallopian tube, ready to meet sperm. Common symptoms: Some women experience mild pain or cramping on one side of the lower abdomen. Purpose: The released egg is ready to be fertilized.
Luteal phase
This phase always occurs between day 14 and day 28 of the cycle, with a possible break of only 1-2 days. Progesterone, stimulated by LH, is the dominant hormone in this phase, preparing the corpus luteum and endometrium for possible implantation of the fertilized egg. The corpus luteum is a structure that forms in the ovary at the site of rupture of the mature follicle and serves to produce hormones characteristic of this phase.
If pregnancy occurs, the fertilized egg implants in the endometrium, and the corpus luteum is preserved and maintains hormone levels. Otherwise, the corpus luteum regresses, and estrogen and progesterone levels rapidly decline until menstruation occurs. If the egg is not fertilized, progesterone levels decline in the final stages, causing the endometrium to degrade and menstruation to begin.
Menstruation
Menstruation is part of the follicular phase. When hormone levels drop, the lining of the uterus (endometrium) undergoes intense degradation because it is no longer needed since conception has not occurred. The amount of blood released can be affected by a variety of factors, including medications, endometrial thickness, blood disorders, and bleeding disorders.
Common symptoms: abdominal cramps, back pain, fatigue and mood swings. Goal: removal of unnecessary uterine tissue, preparing the uterus for the next cycle.
