advertisement
24 February 2011

The menstrual cycle from menarche to menopause

Menstruation has many names but, whatever you call it, it is the term given to cyclical monthly bleeding from the uterus of adolescent girls and pre-menopausal women.

Menstruation has many names (period, monthly cycle, the flow) but, whatever you call it, it is the term given to cyclical monthly bleeding from the uterus of adolescent girls and pre-menopausal women. This regular discharge of blood, tissue, fluid and mucous usually lasts 3 - 6 days.

The cause

  • When an adolescent girl – the average age of onset is between 11 and 16 years – or woman ovulates, a mature egg (one that can be fertilised) is released by one of her two ovaries.
  • If, as it travels along the Fallopian tubes, it is met by sperm, the egg is fertilised and pregnancy may occur. This fertilised egg will then adhere to the lining (endometrium) of the uterus, producing a hormone (BetaHCG) which prevents menstruation by stimulating the ovary to continue producing progesterone and the pregnancy will proceed.
  • However, if there is no fertilisation the endometrium comes away from the uterine wall. This occurs 14 days after ovulation and is due to the falling progresterone levels. The lining disintegrates and passes through the vagina as menstrual flow.

  • Day 1 of bleeding is referred to as Day 1 of the menstrual cycle. This is when the thickened lining (endometrium) starts to shed.
  • Ovulation occurs, on average, on Day 14 of a 28-day cycle. This is when a mature egg is released to travel down the Fallopian tube. The lining of the uterus (endometrium) has thickened in preparation. If no conception occurs, the lining and blood sheds: this is menstruation.

  • If the egg is fertilised by sperm and attaches to the endometrium, a pregnancy begins. (This pregnancy is dated from Day 1 of this menstrual cycle.)
  • If the egg is not fertilised or does not attach, the endometrium begins to break down and the menstrual cycle starts again.

 
NEXT ON HEALTH24X
advertisement

Read Health24’s Comments Policy

Comment on this story
0 comments
Comments have been closed for this article.

Live healthier

Lifestyle »

E-cigarettes: Here are five things to know

E-cigarettes have become hugely popular in the past decade, but a rash of vaping-linked deaths and illnesses in the US is feeding caution about a product that's already banned in some places.

Allergy »

Ditch the itch: Researchers find new drug to fight hives

A new drug works by targeting an immune system antibody called immunoglobulin E, which is responsible for the allergic reaction that causes hives.

advertisement