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Understand the Phases in the Menstrual Cycle

Menstruation is a natural thing experienced by a woman. Although it has been experienced since was a teenager, not all women know what happens in the body during the menstrual cycle.

Menstrual cycles are changes in a woman's body, especially in the reproductive organs. Menstruation occurs when the lining of the uterine lining (endometrium) is thickened due to the absence of fertilization of the egg. Menstrual cycles vary from woman to woman, can occur between 23-35 days, but the average menstrual cycle is 28 days.

Hormones That Affect Phases in the Menstrual Cycle

The menstrual cycle is divided into several phases that are regulated by five hormones in the body. The hormones in question include:

  • Estrogen

Hormones produced in the ovary play an important role in the body, especially in ovulation in the female reproductive cycle. The hormone estrogen also plays a role in adolescent body changes during puberty and is involved in the re-formation of the lining of the uterus after the menstrual period.

  • Progesterone

This hormone works in conjunction with estrogen to maintain the reproductive cycle and maintain pregnancy. Similar to estrogen, progesterone is also produced in the ovaries and plays a role in the thickening of the uterine wall.

  • Gonadotrophin-releasing hormone-GnRH hormone

Produced by the brain, this hormone helps stimulate the body to produce follicular stimulating hormones and lutein hormones.

  • Luteinizing hormone (LH)

The egg and ovulation process is produced by the ovary thanks to stimulation from this hormone.

  • Follicle-stimulating hormone (FSH)

This hormone functions to help the egg in the ovary mature and ready to be released. This hormone is produced in the pituitary gland in the lower part of the brain.

Phases in the Menstrual Cycle

First Phase - Menstruation

The first phase of the menstrual cycle usually takes 3-7 days. At this time, the lining of the uterine lining breaks down into menstrual blood. The amount of blood that comes out during menstruation ranges between 30-40 ml in each cycle.

On the first day until the 3rd day, menstrual blood that comes out will be more. At this time, usually, women will feel pain or cramps in the pelvis, legs, and back.

Pain in the abdomen that is also often felt in the first days of menstruation is triggered due to contractions in the uterus. This uterine muscle contraction occurs due to an increase in the hormone prostaglandin during menstruation.

The strong contractions in the uterus can cause oxygen supply to the uterus and do not run smoothly. Because of this lack of oxygen, cramps or abdominal pain are felt during menstruation.

Although it causes pain, the contractions that occur during menstruation actually function to help push and remove the lining of the uterine lining which breaks down into menstrual blood.

The decay of the lining of the uterine lining is also caused by a decrease in estrogen and progesterone levels. At the same time, follicular stimulating hormone (FSH) begins to increase slightly and provokes the development of 5-20 follicles (pockets containing ovaries) in the ovary. Of the several follicles that develop, there is only one follicle that continues to develop to produce estrogen.

It is during this menstrual period that your estrogen hormone will be at a low level. So do not be surprised if you are emotionally easier to be angry or offended during menstruation.

Second Phase - Pre-ovulation

The follicular or pre-ovulatory phase begins on the first day of menstruation. On your first day of menstruation, at that time also the follicle-stimulating hormone (FSH) begins to increase.

This condition starts when the hypothalamus sends signals to the pituitary gland and releases a chemical called gonadotropin-releasing hormone (GnRH).

This hormone encourages the pituitary gland to produce elevated levels of the hormones lutein (LH) and FSH. FSH is responsible for stimulating the ovaries to produce 5-20 small bags called follicles.

Each follicle contains an immature egg. In the process, only the most healthy egg cells will eventually mature. While the remaining follicles will be absorbed back into the body.

Mature follicles will trigger estrogen surges to thicken the lining of the uterus. The thickened uterine lining is conditioned to create a nutrient-rich environment for the embryo (future fetus) to grow.

This phase lasts around 11-27 days, depending on your monthly cycle. But generally, women experience the follicular phase for 16 days.

Third phase - Ovulation

Increasing estrogen levels during the follicle or pre-ovulation phase triggers the pituitary gland to release the luteinizing hormone (LH). In this phase, the ovulation process begins. Ovulation usually occurs in the middle of the cycle, which is about 2 weeks or more before menstruation begins.

Ovulation is the process when the ovaries release a mature egg cell. The egg then moves to the fallopian tube to the uterus to be fertilized by sperm. The life span of an egg cell is usually only about 24 hours to meet the sperm.

The ovulation phase is the only best opportunity during the menstrual cycle for you to get pregnant. After 24 hours, the egg that does not meet the sperm will die.

When ovulating, women usually experience thick, sticky vaginal discharge that is clear as egg white. Basal body temperature will also increase.

Basal body temperature is the lowest temperature reached during rest or during sleep. Normal body temperature is in the range of 35.5 to 36º Celsius. But during ovulation, the temperature will rise to 37 to 38º Celsius.

Basal temperature is measured by a thermometer placed in the mouth, vagina, or anus. If you are planning to become pregnant, be sure to measure your body temperature every day at the same location and time for 5 minutes.

Basal temperature measurements are best done in the morning after waking up and before starting any activity.

The fourth phase - Luteal

When the follicle releases its egg, its shape changes into the corpus luteum. The corpus luteum releases the hormones progesterone and estrogen. The increased hormone in the fourth phase of menstruation serves to keep the lining of the uterus thick and ready to be implanted with a fertilized egg.

If positive is pregnant, the body will produce human chorionic gonadotropin (hCG). This hormone helps maintain the corpus luteum and keeps the uterine lining thick and permanently.

But if you are not pregnant, the corpus luteum will shrink and be absorbed by the lining of the uterus. Then estrogen and progesterone levels will slowly decrease, making the uterine lining eventually detached and decays.

If positive is not pregnant, in this phase you will experience symptoms called premenstrual syndrome (PMS). Various symptoms that usually appear are:

  • Bloated
  • Swollen and sore breasts
  • Moods change easily
  • Headache
  • Gain weight
  • Feel like to keep eating
  • Hard to sleep

The luteal phase usually lasts for 11 to 17 days. However, the average woman experiences it for 14 days.

If you experience irregular menstrual cycles, menstruation for more than 7 days, or no menstruation for 3 months in a row, consult your obstetrician immediately. The doctor will do an examination to find out your condition. That way, any irregularities that emerge can be immediately detected and given the right treatment.



  1. Better Health Channel. Department of Health & Human Services, State Government of Victoria, Australia. Menstrual cycle.
  2. Marquette University. Phases of the Menstrual Cycle. 
  3. WebMD. (2018). Understanding Ovulation & Fertility: Facts to Help You Get Pregnant. 
  4. Mayoclinic (2019). Menstrual Cycle: What’s Normal What’s Not.

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Is a health and wellness enthusiast. In him free time, she loves to travel and taste different types of teas.

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