What are the phases of the menstrual cycle?

Menstrual Phase: Shedding of the uterine lining (period). Follicular Phase: Preparation of an egg in the ovaries and thickening of the uterine lining. Ovulation: Release of a mature egg around mid-cycle. Luteal Phase: Hormonal changes to support pregnancy or prepare for the next period if fertilization doesn’t occur.

Is it normal to have irregular periods?

Occasional irregular periods are normal, especially during puberty, after childbirth, or near menopause. Persistent irregularities may indicate conditions like PCOS, thyroid issues, or hormonal imbalances.

Can exercise affect the menstrual cycle?

Yes, intense physical activity can lead to missed or irregular periods, a condition known as exercise-induced amenorrhea. Moderate exercise can help alleviate menstrual symptoms.

What is PMS (Premenstrual Syndrome)?

PMS refers to physical, emotional, and behavioral symptoms occurring before the period, such as bloating, mood swings, and fatigue. Severe PMS is known as PMDD (Premenstrual Dysphoric Disorder).

Can stress impact my menstrual cycle?

Yes, stress can disrupt hormonal balance, leading to delayed, skipped, or irregular periods.

Is it normal to have blood clots during a period?

Small clots (about the size of a quarter) can be normal. However, frequent or large clots may indicate a condition like fibroids or heavy menstrual bleeding (menorrhagia).

What is the relationship between periods and birth control?

Hormonal birth control methods (like pills or IUDs) can regulate or stop periods. However, some methods might cause spotting or irregular bleeding initially.

Why do periods stop during pregnancy?

Periods stop because the body produces hormones (like hCG and progesterone) to maintain the uterine lining for the developing baby.

Menstrual Cycle: Phases, Hormones, Hygiene

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NEET Biology

Menstrual Cycle

The menstrual cycle is a natural, recurring process that prepares the female body for potential pregnancy. Typically lasting around 28 days, though it can vary, the cycle involves complex hormonal changes that regulate the growth and release of an egg (ovulation) and prepare the uterus for pregnancy. The cycle has four main phases: menstruation, the follicular phase, ovulation, and the luteal phase. If fertilization does not occur, the uterine lining sheds, resulting in menstruation. This cycle is crucial for reproductive health and is controlled by interactions between hormones from the brain and the ovaries.

1.0Introduction

The reproductive cycle in the female primates (e.g. monkeys, apes and human beings) is called menstrual cycle.
The first menstruation begins at puberty and is called menarche.
In human females, menstruation is repeated at an average interval of about 28/29 days, and the cycle of events starting from one menstruation till the next one is called the menstrual cycle.
In the Menstrual cycle the female body prepares itself for a possible pregnancy.
If the pregnancy does not occur, then the body aborts all preparation done and restarts the preparation for pregnancy again in a monthly cyclic manner.
Menstrual cycle has three main phases:
(i) Bleeding phase or menstruation phase.
(ii) Proliferative/preovulatory/follicular phase or oestrogenic phase.
(iii) Secretary/post ovulatory/luteal phase or progesteronic phase.

2.0Hormones Associated With Menstrual Cycle

	Estrogen	Progesterone (Anti-abortion or Pregnancy hormone)
1.	Endometrial hyperplasia	Increases secretory nature of endometrium (Development of glands)
2.	Increases vascularity of endometrium	Increases adhesive nature of endometrium
3.	Myometrial hypertrophy	Decreases myometrial contraction
4.	Ultimately increase thickness of uterine wall	Maintains thickness of uterine wall

3.0Different Phases Of Menstrual Cycle

Hormone Levels	Ovarian changes	Uterine changes
1. BLEEDING PHASE (4–5 DAYS)
On day 1 of the cycle, levels of all four hormones (FSH, LH, estrogen and progesterone) are low.	Initially corpus luteum/corpus albicans (of previous cycle) disintegrates completely.	Due to withdrawal of sex hormones, prostaglandins are formed in the uterus which cause vasoconstriction. It leads to decreased blood supply to stratum functionalis that results in its degeneration and separation.
Due to absence of negative feedback of estrogen and progesterone, levels of FSH and LH start increasing in the terminal stage of this phase.	Then 6-12 primary follicles are stimulated for further follicular development.	Prostaglandins also cause contractions in myometrium which leads to sloughing of dead endometrial tissue (stratum functionalis) with blood from the uterine cavity through vagina. This bleeding continues for 4-5 days, and clotting does not occur due to the presence of fibrinolytic enzymes. Average 40 to 80 ml blood loss per cycle.

Hormonal changes	Ovarian changes	Uterine changes
2. FOLLICULAR/PROLIFERATIVE/ESTROGENIC/PREOVULATORY PHASE
The secretion of gonadotropins (LH and FSH) increases gradually. The level of estrogen in the blood continues to rise throughout most of this phase, reaching a maximum (peak) in the terminal stage of this phase.	During this phase, the primary follicles in the ovary grow to become a fully mature Graafian follicle. [1-2 secondary follicles → 1 tertiary follicle → 1 Graafian follicle] Follicular development is stimulated by increasing secretion of gonadotropins. Growing follicles secrete estrogen.	Uterine bleeding is stopped. Endometrial hyperplasia. i.e. formation of stratum functionalis.
Due to positive feedback of this high level of estrogen, both LH and FSH attain a peak level in about the middle of the cycle. Progesterone level remains low until just before ovulation.	Swelling of Graafian follicle due to increase in antral fluid. Maximum level of LH during the midcycle is called LH surge and due to this synthesis of proteolytic enzymes resulting in rupturing of Graafian follicle and ovarian wall resulting in ovulation.	Myometrial hypertrophy i.e. increase in size of myometrial cells. The thickness of the uterine wall is increased.

Lack of menstruation may be indicative of pregnancy. However, it may also be caused due to some other underlying causes like stress, poor health etc.
In human beings, menstrual cycles begin from approx. 13 years of age; that is termed as menarche and menstrual cycles cease around 50 years of age; that is termed as menopause. Cyclic menstruation is an indicator of normal reproductive phase.

4.0Menstrual Hygiene

Maintenance of hygiene and sanitation during menstruation is very important.
Take a bath and clean yourself regularly. Use sanitary napkins or clean homemade pads.
Change sanitary napkins or homemade pads after every 4-5 hrs as per the requirement.
Dispose of the used sanitary napkins properly wrapping it with a used paper.
Do not throw the used napkins in the drainpipe of toilets or in the open area. After handling the napkin, wash hands with soap.

5.0Symptoms Before the Period (Premenstrual Phase or PMS)

Physical Symptoms

Bloating
Breast tenderness or swelling
Headaches or migraines
Joint or muscle pain
Fatigue
Changes in appetite (cravings or increased hunger)
Acne breakouts
Constipation or diarrhea

Emotional Symptoms

Mood swings
Irritability or anger
Anxiety or depression
Trouble concentrating
Sleep disturbances

Irregular Symptoms to Watch For

While many symptoms are normal, seek medical advice if experience:

Extremely heavy bleeding (changing pads or tampons every 1-2 hours)
Severe pain that affects daily activities
Prolonged bleeding (lasting more than 7 days)
Significant changes in cycle length or missed periods unrelated to pregnancy
Sudden onset of irregular cycles after being previously regular

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