The role of reproductive hormones in the menstrual cycle

Greg Foot describes the role of hormones in the menstrual cycle

The menstrual cycle is a recurring process which takes around 28 days. During the process, the lining of the uterus is prepared for pregnancy. If implantation of the fertilised egg into the uterus lining does not happen, the lining is then shed. This is known as menstruation or having a period.

Several hormones control this cycle – for example, they are involved in controlling the release of an egg each month from an ovary and changing the thickness of the uterus lining.

  • Oestrogen produced by the ovaries, is involved in repairing and thickening the uterus lining.
  • Progesterone maintains the lining, preparing the uterus for pregnancy. If a woman becomes pregnant, the placenta also produces progesterone. This maintains the lining of the uterus during pregnancy and means that menstruation does not happen. If a woman is not pregnant, her progesterone levels will fall towards the end of her menstrual cycle. This triggers menstruation.