Question

why does menstruation occur?​

Answer 1

Answer:

What Causes 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.

Answer 2

Answer:

Menstruation occurs to remove the unfertilized egg ,the thick and spongy lining formed on the uterine wall

Explanation:

it marks one end of one cycle and to restart the next phase of egg maturation and provide a second chance for fertilisation of egg.