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Menstrual Cycle

Female Hormonal Levels

Days 1 to 5
The lining of the womb (known as the endometrium) is shed during menstruation (monthly period).

Days 6 to 14
The lining of the womb gradually builds up again and, under the influence of oestrogen, becomes thick and juicy ready to receive and nourish a fertilised egg.
Oestrogen stimulates the mucus produced by your cervix (neck of the womb) to become thin and slippery so sperm can swim through it.

Days 15 to 28
Rising levels of progesterone from the corpus luteum increase the blood supply to the lining of your womb making it the perfect environment for a fertilised egg.

If the egg is not fertilised - or is fertilised but doesn't attach itself to the lining of the womb - the egg breaks down. The corpus luteum shrinks and progesterone levels plummet. This causes the blood vessels in the lining of the womb to break up, the walls of the womb to contract, and the menstrual cycle to start again.