”Exploring Comprehensive Guide Regarding Menstrual Cycle! All You Need To Know In 2024”

Introduction:

The menstrual cycle is a natural process in a woman’s body each month. It is a series of changes that prepare the body for pregnancy. The cycle typically lasts about 28 days but can vary from person to person. The main events in the menstrual cycle include the release of an egg from the ovaries, the thickening of the uterine lining to support a possible pregnancy, and the shedding of this lining if pregnancy doesn’t occur, leading to menstruation.

Hormones play a crucial role in regulating these changes. Menstruation, commonly known as a period, occurs when the combination of RBCs along with plasma and epithelial tissues discharge from the uterus through the vagina. The menstrual cycle is an essential and healthy physiological feature of a woman’s life, and it usually starts during puberty and continues until menopause.

Duration and frequency:

The duration and frequency of a normal, healthy menstrual cycle varies depending on the age and overall health of the individual. However, the cycle average is 28 days. It can be as short as 20 days; in some women, it is longer than 35 days.

Usually, the frequency of menstruation is from 2 to 7 days. It varies in every woman. In the initial few years after menarche (initiation of menstruation), the cycle becomes much longer, but as the age advances, it becomes shorter and more regular.

Also explore: Pink moon menstruation.

Significance of the cycle:

There are many significance of the female reproductive cycle:

1. Only one single ovum is released from the ovaries each month.
2. The uterine endometrium prepares itself in advance for the implantation of the fertilized embryo at the essential time of the month.
3. The menstrual cycle is crucial for reproductive health as it prepares the body for potential pregnancy each month.
4. Regular menstrual cycles indicate a proper balance of hormones, such as estrogen and progesterone, which is necessary for overall health.
5. Menstruation helps maintain uterine health by shedding the lining and preventing the buildup of tissues that could lead to health issues.
6. Estrogen, a hormone in the menstrual cycle, is also crucial for maintaining bone density. Regular cycles contribute to better bone well-being.
7. Hormonal changes during the menstrual cycle can alter mood and emotions. Understanding these changes promotes emotional well-being and self-care.
8. Irregularities in the menstrual cycle can sometimes indicate underlying health issues, making it an early warning system for specific conditions.

What are the phases of the menstrual cycle?

The day count of the menstrual cycle begins from the 1st day of menstruation when bl**d excrete from the vagina. The entire cycle is divided into 4 phases, which are:

• Menstrual phase (from day 1st to day 5)
• Follicular phase (from day 1st to day 13).
• Ovulation phase (day 14).
• Luteal phase (from day 15 to day 28).

Menstrual phase:

• The menstrual phase is the 1st phase of the female cycle. This phase starts when the previous cycle’s ovum is unable to fertilize. During this phase, the endometrium sheds along with blood. 
• Menstruation is initiated as a consequence of the down surge of estrogen and progesterone levels, and this will result in the decline of stimulation of endometrial cells and rapid involution of the endometrium, which is about 65% of its previous thickness.
• After 24 hours of proceeding with the onset of menstruation, the tiny blood vessels leading to the mucosal layer of the endometrium became vasospasmic. This vasospasm caused a decline in the nutrient supply to the endometrium, and the loss of hormonal stimulation initiated necrosis (tissue death) of the endometrial lining.
• As a result, blood seeps into the vascular layer of the endometrium, and the hemorrhagic area proliferates throughout 24 to 36 hours.
• Gradually, the necrotic outer layer of the endometrium separates from the uterus. After the onset of menstruation, the superficial layers of the endometrium have desquamated. The mass of desquamated cells and blood, along with the contractile effects of prostaglandins, act simultaneously to begin uterine contraction and cause expulsion of the uterine contents.

Nature of flow of blood:

• During normal menstruation, approximately 40ml of blood and an additional 35ml of serous fluid become lost. The menstrual blood is non-cloting in nature due to the presence of fibrinolysin.
• Blood loss ceases within 4 to 7 days after menstruation, and the entire endometrium becomes re-epithelialized.

(Irregular menstruation is an indication of several disorders, including polycystic ovarian syndrome, uterine fibroids, etc. It is recommended to keep a strict eye on the duration, frequency, and intensity of menstruation).

Read also: Plasma donation and menstrual cycle.

Follicular phase:

• After the onset of puberty, FSH and LH from the anterior pituitary gland begin to secrete in significant quantities. The ovaries and some of the follicles in them start to grow—additional layers of granulosa cells across the follicles (primary follicles).
• During the 1st few days of the cycle, the concentration of FSH (follicle-stimulating hormone) and LH (luteinizing hormone) increases slightly. FSH is greater than LH. These hormones, especially FSH, cause monthly accelerated growth of 6 to 12 primary follicles.
• After the early proliferative phase of growth lasts a few days, granulosa cells secrete a follicular fluid containing a high concentration of estrogen.
• The ovum, along with the follicle, enlarges. The ovum remains embedded in the granulosa cell mass at one follicle pole.
• After a week of growth, before ovulation, one of the follicles begins to out and grow further. All the remaining developing follicles are involuted through a process called atresia (the degeneration of those ovarian follicles that do not ovulate).
• The single follicle reaches a diameter of about 1 to 1.5 cm at ovulation and is called the mature follicle.

Why atresia is essential?

• The process of atresia is essential because it typically allows only one of the follicles to grow large enough each month to ovulate; this usually prevents more than one child during each pregnancy.

Ovulation phase:

• Before ovulation, the protruding outer wall of the follicle swells, and a small area in the center of the follicular capsule called a stigma protrudes like a nipple.
• In 30 minutes, fluid begins to ooze from the follicle through the stigma, and later, in 2 minutes, the stigma ruptures, allowing more viscous fluid to become evaginated from the follicle to the outside.
• LH is necessary for the final follicular growth and ovulation. In the absence of LH, even if a considerable quantity of FSH is available, the follicle will not progress till the stage of ovulation.
• About two days before the ovulation, the FSH and LH act together to induce rapid follicle swelling. The LH also affects explicitly the Granulosa and Theca cells (another mass of cells within the follicle). Therefore, the frequency of estrogen secretion begins to fall precisely one day before ovulation and enhances progesterone secretion.
• LH is responsible for the furious secretion of progesterone. Within a few hours, two important events take place necessary for ovulation:

1. The theca externa (capsule of the follicle) begin to release proteolytic enzymes from lysosomes; these cause the dissolution of the follicle capsule outer wall and subsequently weaken the entire wall, resulting in swelling of the entire follicle and degeneration of stigma.
2. New blood vessels are rapidly growing inside the follicle wall, and prostaglandins (a local hormone that causes vasodilation) are secreted in the follicle tissues.

• These two actions cause plasma transudation across the follicle. The final result is the follicle rupture, and the release of the ovum, which is a product of the follicle, travels into the fallopian tube.

Luteal phase:

The luteal phase is the last phase of the ovarian cycle, corresponding to the secretory phase of the uterine cycle. 

Hormonal shifts in the luteal phase:

• The pituitary gland’s secretion of FSH and LH causes the remaining part of the empty follicle to transform into the Corpus Luteum, an essential site of progesterone secretion. Progesterone also triggers estrogen production. 
• The corpus luteum cells are responsible for the fall of FSH and LH because the luteum cells secrete a small amount of the hormone Inhibin, which stops the secretion of FSH and LH from the anterior pituitary gland.
• In return, low plasma concentrations of FSH, L, and H cause atrophy of the corpus luteum and cause involution.
• Currently, the cessation of estrogen, progesterone, and inhibin secretion from the corpus luteum stops the feedback inhibition of FSH and LH secretion from the anterior pituitary gland (due to luteum degeneration). It will again cause FSH and LH secretion, which initiate the new follicles and begin a new ovarian cycle. 
• The lack of progesterone and estrogen secretion now leads to menstruation through endometrium.

 

Preparation of the uterus for potential pregnancy:

As discussed earlier, the corpus luteum is responsible for progesterone secretion, crucial in preparing the uterus for a possible pregnancy. Progesterone helps thicken the uterus lining, making it a cozy place for a fertilized egg to attach and grow. Progesterone makes secretory changes across the uterus possible, which is mandatory for fertilized embryo implantation. It is important to note that progesterone is released for a limited period by luteum cells and is not enough to maintain an entire pregnancy. So when the placenta is established in the endometrium, it releases the human chorionic gonadotropin hormone essential for the maintenance of pregnancy.

The Menstrual blood and plasma:

The menstrual blood also possesses plasma same as found in the peripheral blood however the concentration of different hormones like FSH, prolactin, LH, and Progesterone varies. For example, the menstrual plasma prolactin levels rise as compared to systemic blood plasma on the first day of menstruation  (63.3 +/- 14.7 and 12.1 +/- 2.9 micrograms/L.

Conclusion:

 In summary, the menstrual cycle is a regular and natural process in a woman’s life. It involves various phases, from menstruation to the follicular, ovulation, and luteal phases. These phases are influenced by hormonal changes that prepare the body for the potential of pregnancy. Menstruation, or the period, is the body’s way of resetting if pregnancy doesn’t happen. The menstrual cycle is a sign of reproductive health and a crucial aspect of overall well-being. Understanding and appreciating this cycle is vital for women, as it is a normal and essential part of their journey from puberty to menopause. Embracing this natural process helps promote a positive attitude towards women’s health, breaking down stigmas and fostering a better understanding of our bodies.

FAQs:

What are the 4 stages of the menstrual cycle?

The complete menstrual cycle consists of (i) the Menstrual phase lasting an average of 5 days, (ii) the follicular phase lasting on the 13^th day, (iii) ovulation on day 14^th and (iv) the luteal phase from the 15^th day till 28^th day.

What is the full cycle of menstruation?

Menstruation begins with the shedding of the uterine lining (menstrual bleeding). The follicular phase follows, where an egg matures in the ovary and the uterine lining thickens. Ovulation occurs around the middle of the cycle when the mature egg is released. While the luteal phase ensures, the uterine lining is maintained in anticipation of pregnancy, and if no pregnancy occurs, the cycle repeats.

How many periods in a cycle?

For most women, it is only one period of bleeding which usually lasts 5 days and its intensity also varies. However many women experience shorter menstrual cycles so they have more than one period (menstruation phase) in the month.

How many days after your period can you get pregnant?

The possibility of getting pregnant depends on the ovulation which occurs on day 14^th, exactly counted from the first day of menstruation. Experts consider day 13^th to day 16^th as an open window for sperm and chances of fertilization in the fallopian tube.

Can I get pregnant with the 25-day cycle?

The scientists suggested that women who have menstrual cycles shorter than 28 days might face trouble getting pregnant.

Can I get pregnant 2 days after my period?

It’s generally less likely, but it’s not impossible. The menstrual cycle varies among individuals, and the fertile window can differ. While the likelihood of getting pregnant is typically lower right after your period, sperm can survive for several days in the female reproductive system. If you have a shorter menstrual cycle, it’s possible that you could ovulate earlier.

How long is ovulation?

The phase of ovulation occurs on day 14^th. During this phase egg is released from the ovary reaches the fallopian tube and stays here for 24 hours. If fertilization does not occur during this time, the egg dies and is released along with the uterine lining.

References: 

https://www.healthline.com/health/womens-health/stages-of-menstrual-cycle#follicular

https://my.clevelandclinic.org/health/articles/10132-menstrual-cycle

https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/menstrual-cycle

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3987350/#:~:text=Indeed%2C%20it%20induces%20secretory%20changes,quiescence%20and%20suppresses%20uterine%20contractions.