The normal menstrual cycle lasts 28–29 days, but this varies across people and cycle to cycle. The period cycle is measured from the first day of your period to the day before the start of your next period.

Girls often begin their menstrual cycle (menarche) between the ages of 11 to 14 years old. By this stage, more sexual characteristics such as pubic hair and budding breasts have grown.

Hormones and menstruation

The menstrual cycle is intricate and is regulated by a variety of glands and the hormones produced by these glands. The hypothalamus, a brain structure located nearby, stimulates the pituitary gland to release chemicals that signal the ovaries to produce the sex hormones oestrogen and progesterone.

The menstrual cycle is a feedback system, which implies that the activity of one structure or gland affects the activity of others.

Menstrual Cycle Phases

The menstrual cycle phase is divided into four distinct phases:

  • Menstruation
  • Adolescent follicular phase
  • Ovulation
  • Luteal phase.

Menstruation phase

Menstruation is the process by which the uterus’s thicker lining (endometrium) is eliminated from the body via the vagina. Menstrual fluid is composed of blood, cells from the uterine lining (endometrial cells), and mucus. A menstruation typically lasts between three to seven days.

To absorb menstrual flow, sanitary pads or tampons are used. Both pads and tampons must be changed on a regular basis (at least every four hours). Tampon use has been linked to an increased chance of developing a rare condition known as toxic shock syndrome (TSS).

Follicular phase

The follicular phase of menstruation begins on the first day of menstruation and continues until ovulation occurs. The brain stimulates the pituitary gland to release follicle stimulating hormone (FSH). This hormone causes the ovary to generate between five and twenty follicles (tiny nodules or cysts) that bead on the surface.

Each follicle contains a developing egg. Typically, just one follicle matures into an egg, while the remaining follicles die. This may occur on the tenth day of a 28-day cycle. The development of the follicles causes the uterine lining to thicken in preparation for probable pregnancy.

Ovulation phase

Ovulation is the process through which a developed egg is released from the ovary’s surface. This normally occurs in the middle of the cycle, around two weeks before menstruation begins.

The growing follicle stimulates the production of oestrogen during the follicular phase. The brain’s hypothalamus detects these increases and produces a substance called gonadotropin-releasing hormone (GnRH). This hormone stimulates the pituitary gland to produce increased quantities of luteinising hormone (LH) and follicle stimulating hormone (FSH).

Ovulation is triggered within two days when LH levels are elevated. By means of waves of small, hair-like projections, the egg is funneled through the fallopian tube and toward the uterus. The normal egg has a lifespan of approximately 24 hours. Unless it comes into contact with a sperm during this time period, it will perish.

When trying to conceive, you can increase your chances of pregnancy by learning about ovulation and the menstrual cycle’s ‘fertile window.’ Continue reading to learn more about ovulation and the reproductive window.

Luteal phase

The egg ruptures from its follicle during ovulation, but the ruptured follicle remains on the ovary’s surface. The follicle undergoes a transformation into a structure called the corpus luteum over the next two weeks. This structure initiates the release of progesterone and trace levels of oestrogen. This cocktail of hormones preserves the uterus’s thicker lining while waiting for a fertilized egg to adhere (implant).

When a fertilized egg implants in the uterine lining, it produces the hormones necessary for the corpus luteum to remain intact. This contains human chorionic gonadotrophin (HCG), a hormone discovered during a pregnancy urine test. The corpus luteum continues to produce the elevated quantities of progesterone required to maintain a thicker uterine lining.

Without pregnancy, the corpus luteum withers and dies, often on day 22 of a 28-day cycle. The decrease in progesterone levels results in the uterine lining falling away. This is referred to as menstruation. After that, the cycle is repeated.


Menstrual difficulties that are frequently encountered:

Among the most frequent menstruation disorders are the following:

  • PMS — hormonal changes before menstruation can cause a variety of negative symptoms in women at risk, including fluid retention, headaches, fatigue, and irritability. Exercise and dietary adjustments are among the suggested treatment strategies.
  • Dysmenorrhoea is the medical term for unpleasant periods. Certain hormones are thought to cause the uterus to squeeze more forcefully than necessary in order to release its lining. There are several treatment options available, including pain medicine and the oral contraceptive pill.
  • Menstrual bleeding that is excessive (formerly called menorrhagia) — if left untreated, this can result in anemia. Oral contraceptives and a hormonal intrauterine device (IUD) are available as treatment alternatives.
  • Amenorrhoea – or the absence of menstruation – is a condition. Except during puberty, pregnancy, nursing, and postmenopause, this is regarded abnormal. Possible causes include an abnormally low or excessively high body weight, as well as intense exercise.