Oestrogen and progesterone in the control of the menstrual cycle

Several hormones are involved in the menstrual cycle of a woman:

The menstrual cycles last for approximately 28 days, and graphs can be used to follow changes to the hormones during this process.

A diagram representing the menstrual cycle and hormone levels

Describe the relationship between the different hormones during the 28 days.

Days 1 to 12 – oestrogen gradually increases and peaks approximately on the 12th day. Progesterone, LH and FSH stay approximately at the same levels and begin to increase slightly from around day 12.

FSH and LH patterns are very similar and peak during ovulation at approximately 14 days during this cycle. They drop sharply on day 15 and stay constant until day 28.

Oestrogen drops during days 13 and 14, and progesterone continues to gradually increase until about day 21, when it slowly beings to decrease again. Oestrogen mirrors this shape and also has a second lower peak at about day 21.