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Understanding your period (menstruation)
A period is a woman's monthly bleeding. It is the part of the menstrual cycle whereby the shedding of the uterus lining results in a discharge of menstrual blood from the uterus through the cervix and vagina.1

A normal menstrual cycle

A menstrual cycle is counted from the first day of bleeding. The average menstrual cycle is 28 days long and the typical duration of menstruation is 3 to 7 days. However, imbalance in the female hormones (oestrogen and progesterone) may result in a deviation from the regular cycle, leading to variability in the length of cycles that could range from 21 to 35 days in adults and from 21 to 45 days in young teens.1

What happens in a menstrual cycle?

During the first 14 days of a menstrual cycle, the levels of female hormones (oestrogen and progesterone) increase and cause the lining of the uterus (womb) to thicken. This is to prepare the uterus environment to nourish the embryo if a pregnancy occurs.1

At the 14th day, ovum (egg) in the ovary matures and leaves the ovary. This process is known as ovulation.1 The egg travels through the fallopian tube to the uterus. A woman’s egg has a high chance of being fertilized during 3 days before or on the day of ovulation.

Pregnancy commences when the egg is fertilized by a man’s sperm cell and the fertilized egg attaches to the uterine wall. If the egg is not fertilized, it will be broken down and absorbed by the body. The hormone levels also drop. The thickened lining of the uterus is then shed during menstruation.1


  1. US Department of Health and Human Services. Menstruation and the menstrual cycle fact sheet. Available at: http://www.womenshealth.gov/publications/ our-publications/fact-sheet/menstruation.html. Accessed 29 September, 2015.