Your body's hormones control the menstrual cycle. When the level of the oestrogen hormone in the body increases, the ovaries will release an egg (ovulation).
In the second half of the cycle, the levels of progesterone hormone will increase and this gets the womb ready for pregnancy.
If pregnancy doesn't occur, oestrogen and progesterone levels will drop. This hormonal change causes the lining to be shed from the womb which causes a period.
Contact us in Urdu
You can contact our health information team using Language Line (0800 22 44 88). You'll have a three-way conversation with the call handler to get the advice you need.
Find out more about Language Line.