Why do girls get Periods ?!

Best Answer - Chosen by Voters

Well, basically the womb lining thickens in order to accommodate a fertilised egg, allowing it to grow into a baby. If no egg is fertilised then the womb lining is not needed, so it sheds - which is what your period is. If the womb lining didn't thicken, then the womb is a hostile environment to a fertilised egg, and it wouldn't attach and grow. We as a race wouldn't be able to reproduce. End of life.

Well, if your religious, then god cursed eve for giving adam the apple and god said something like"eve, may you bore many children and live caring for these children for the rest of your life."
If you aren't religious then let me draw it out for you. You ovulate for two weeks. While your ovulating your vaginal walls get covered with blood and tissue so if your egg gets fertilized it can stick to the blood and tissue and grow a baby. If the egg is not fertilized then you loose the blood and tissue and its called your period.

A period is shedding the lining of your womb to keep it healthy so we can conceive a baby!