The menstrual cycle

The four phases of the menstrual cycle are:

  • menstruation,
  • the follicular phase,
  • ovulation
  • the luteal phase

It is a complex cycle that is controlled by many glands and the hormones that these glands produce.

The average length of the menstrual cycle is 28 days, but this can vary between individuals and from one cycle to the next.

Common menstrual problems include heavy or painful periods and premenstrual syndrome (PMS).

Menstrual cycle

menstrual cycle menstruation luteal follicular ovulationphase


Menstruation is the time of month when a uterus sheds its lining (endometrium), causing menstrual fluid to flow from the body through the vagina. Menstrual fluid contains blood, cells from the lining of the uterus (endometrial cells) and mucus. Menstruation periods usually last about 3 to 7 days, but every body is different. Levels of estrogen and progesterone are low.

Managing menstrual periods

Regular periods are a sign that your body is working normally. You should have regular periods unless you are pregnant, breastfeeding, postmenopausal, or have a medical condition that causes your periods to stop. Irregular, painful, or heavy periods may be signs of a serious health problems. Visit a local health service or your doctor to work with you to help get your periods more regular.

Sanitary pads or tampons are used to absorb the menstrual flow. Both pads and tampons need to be changed regularly (at least every four hours). Using tampons has been associated with an increased risk of a rare illness called toxic shock syndrome (TSS). Reusable options include period panties and menstrual cups.

Follicular phase

The follicular phase is the time between the first day of menstrual period and ends with ovulation. Prompted by the hypothalamus, the pituitary gland releases follicle stimulating hormone (FSH) and levels of estrogen rises. FSH tells the ovaries to prepare an egg for ovulation.


The release of the egg from the ovary, mid-cycle. Estrogen peaks just beforehand, and then drops shortly afterwards.

Luteal phase

The time between ovulation and before the start of menstruation, when the body prepares for a possible pregnancy. Progesterone is produced, peaks, and then drops.

Further reading