Your Menstrual Cycle

Your Menstrual Cycle

A 28 day cycle consisting of 3 phases during which the endometrium (inner lining of the uterus) Goes through certain changes to prepare for implantation of a fertilized egg.

Menstrual phase:

Usually occurring on days 1 to 5
(The menstrual period, the curse (not recommended), big red, or Aunt Red) Menstruation will begin on day 1 of your cycle and will last between 3 to 8 days. Estrogen and progesterone levels fall because the follicle that produced them degenerates. This causes the blood vessels supplying the thickened wall of the endometrium to constrict. This cuts off the blood supply causing the thickened wall to fragment as the tissue dies. These tissue fragments along with some blood empties out of the uterus and through the vagina. Typically around a few tablespoons to about half a cup of blood and tissue dribble out slowly during menstruation. The second day of the menstrual flow is usually the heaviest. During and a few days before menstrual flow one might experience cramps Ð slight tight pains around the uterus. 4 to 5 days prior to the menstrual flow women may start to experience Premenstrual Syndrome (PMS). (This is what people refer to when saying, "It must be that time of the month.")

Proliferative phase: days 5 to 14

The low levels of estrogen and progesterone during the menstrual phase, cause the hypothalamus (a part of the brain to produce GnRH (gonadotropin-releasing hormone). This hormone causes the pituitary to release FSH (follicle-stimulating hormone) and LH (luteinizing hormone). These hormones stimulate the growth of around 25 follicles inside the ovaries. The growing follicles release estrogen causing the eggs inside them to grow. This estrogen travels through the blood from the ovaries to the uterus, stimulating the repair and growth of the endometrium. As a result the endometrium becomes thicker and spongier. During this time usually only one egg and its surrounding follicle fully matures. At the end of the proliferative stage, this follicle bulges from the side of the ovary.

Secretory phase: days 14 to 28

Around day 14 the mature follicle and a small spot on the surface of the ovary ruptures releasing an egg the size of a grain of sand. This process is called ovulation. The egg is funneled into the fallopian tube by petal-like projections called fimbriae, and proceeds down the fallopian tubes for the next 4 days. Inside the ovary, the remaining ruptured follicle seals itself and forms into a corpus luteum gland, which releases progesterone and estrogen. These hormones stimulate further growth of the endometrium and increase its blood supply, resulting in a healthy nutrient-rich environment for the possible implantation of a fertilized egg.

If fertilization does not occur within about 24 to 36 hours after ovulation...
The rising levels of estrogen and progesterone from the corpus luteum turn off the pituitary homornes, FSH and LH, which initially started the growth of the egg. Since fertilization and implantation did not occur, there is no embryo to release more hormones to sustain the corpus luteum. As a result it degenerates, estrogen and progesterone levels drop, and the new monthly cycle begins.

If fertilization occurs within about 24 hours...
(see fertilization and pregnancy)

A note on menstrual cycle irregularity
The first 1 to 2 years of menstruation during puberty is normally irregular. This could mean differences from one period to the next in the amount of blood flow, duration of the period, or length of time between periods.

Once you've established a regular cycle, it can become temporarily irregular due to...

  • Travel to different time zones
  • Vigorous sports
  • Abrupt loss or gain of weight
  • Mental stress
  • Illness
  • Frequently spending time around a woman, whose on a different schedule.
  • Pregnancy, which prevents a period from occurring until after your child's birth


During a woman's forties, her ovaries produce less and less estrogen as her eggs run out. Usually between ages 45 and 55, her periods stop occurring.

Consult a physician if you notice...

  • Heavy menstrual flow for over 7 days
  • Bleeding anytime other than during your period
  • Severe cramps at times other than 1 to two weeks before your period or briefly around ovulation.

Feminine products

Both of the following products function to absorb the blood and tissue from a period. Both are made of a clean soft cotton-like material. A pad (sanitary napkin) is an absorbent circular piece of material placed just outside the opening to the vagina. Most pads have a small adhesive area that sticks to the inside of your underwear. A tampon is an absorbent material that is placed inside the vagina using a plastic applicator that comes with the tampons. These products can be purchased at most drug or grocery stores. Most women carry either tampons or pads in a purse when expecting a period. You might consider carrying a pad in your purse as early as age 9 in case your first period starts away from home.

Premenstrual Syndrome (PMS)

Commonly and sometimes rudely referred to as "that time of the month," as in, "it must be that time of the month."

Symptoms - these may not appear until a woman reaches her 20's or 30's

  • Depression & irritability
  • Mood Swings
  • Headache
  • Insomnia
  • Fatigue
  • Dizziness or disturbance of vision
  • Nausea
  • Swollen sensitive breasts
  • A bloated feeling due to water retention
  • Weight gain due to water retention
  • Clumsiness
  • A low tolerance for alcohol
  • Cravings for sweets
  • Back Pain
  • Breathlessness

To reduce these symptoms...

  • Exercise regularly
  • Eat a healthy diet rich in fiber
  • Cut down on salt
  • Cut down on caffeine and alcohol

If these suggestions don't help and the symptoms are too much for you, visit your doctor. Prescriptions for the pill can regulate your period.

Most women at some time in their lives experience cramps (called dysmenorrhea), characterized by pains in the lower abdomen or lower back. These pains are actually caused by muscle contractions in the wall of the uterus that squeeze the blood vessels supplying the muscle, thus cutting off the muscle's oxygen supply, resulting in cramping. This contraction is stimulated by the excessive secretion of prostaglandins (a hormone involved in childbirth) one week or two before your period begins. Typically cramps start 2 to 3 years after a girl's first period. They are most common in women ages 17 to 25. By the late twenties or after giving birth many women stop experiencing these cramps. 1 in 10 women find their cramps severe enough to interfere with their day.

To reduce pain caused by cramps...

  • Exercise regularly to increase blood flow to the pelvis and uterus
  • Back massage
  • Masturbating to orgasm to increase blood flow to the uterus
  • Over the counter pain remedies advertising relief from cramps such as Aspirin or Ibuprofen.
  • A heating pad on the lower abdomen

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