Menstrual Cycle

By: Gina Brown

What is the Menstrual Cycle?

In females, a mature egg develops and it ovulated from one or two of the ovaries about once every 28 days. Before the mature egg is released from the ovary the endometrium (uterine lining) thickens. This is necessary to receive and hold eggs for embryonic develop. If the egg is not fertilized, the endometrium starts to break down. Eventually the old unfertilized egg and the degenerated endometrium are discharged from the reproductive tract.

Stages of the Menstrual Cycle

  • Follicle Stage- Follicle-stimulating hormone (FSH) is secreted from the anterior lobe of the pituitary glad on day 5 of the menstrual cycle. FSH is then circulated to the ovary via the blood stream. When FSH reaches an ovary it will stimulate several follicles. The estrogen stimulates the endometrium to thicken with mucus and a rich supply of blood vessels. These changes prepare the uterus for the implantation of an embryo. The follicle stage last 10 days
  • Ovulation Stage- When the concentration of estrogen in the female bloodstream reaches a high level, it causes the pituitary gland to stop FSH secretion. Around day 14 of the menstrual cycle, this hormonal combination somehow stimulates the mature follicle to break. When the follicle ruptures, a mature egg is released.
  • Corpus Luteum Stage or Luteal Phase- After Ovulation, LH stimulates the cells of the ruptured follicle to divide quickly. Progesterone prevents the formation of new ovarian follicles by inhabiting the release of FSH. The Corpus Luteum stage last about 14 days.
  • Menstruation Stage- If fertilization does not occur and an embryo is not implanted in the uterus, the progesterone reaches a level in the blood stream that inhibits further LH secretion. As the progesterone level decreases, the lining of the endometrium becomes thinner and eventually breaks down. The menstruation stage starts around day 28 of the cycle and lasts about 4 days.


  • Amenorrhea is the absence of menstruation.
  • Pregnancy, breast feeding, menopause, birth control, medications, lifestyle factors, hormonal imbalance, or structural problems can be the reason it happens.
  • Signs and symptoms include absence of menstrual cycle, breast size changes, weight gain or weight loss, discharge from the breast or change in breast size, acne and increased hair growth in a male pattern, vaginal dryness, voice changes.


  • Dysmenorrhea is painful menstruation that typically involves cramps.
  • Dysmenorrhea cramps are a result of Endometriosis which is when tissue similar to the lining of the uterus is found outside its normal location.
  • Symptoms include pain in lower abdomen hips, lower back or thighs, nausea, vomiting. diarrhea, lightheadedness, or general achiness.

Premenstrual Syndrome (PMS)

  • Premenstrual Syndrome is the physical and emotional symptoms that occur one to two weeks before a woman's menstrual cycle.
  • Premenstrual Syndrome happens because of the change in hormones, chemical changes, and stress and emotional problems.
  • Symptoms include mood swings, tender breasts, food cravings, fatigue, irritability, and depression.