What happens during a period?

A period happens because of changes in hormones in the body. Hormones are chemical messengers. The ovaries release the female hormones estrogen and progesterone . These hormones cause the lining of the uterus (or womb) to build up. The built-up lining is ready for a fertilized egg to attach to and start developing. If there is no fertilized egg, the lining breaks down and bleeds. Then the same process happens all over again.
It usually takes about a month for the lining to build up, then break down. That is why most girls and women get their periods around once a month.

Go back to All about your first period!