because women have the time when they arent cleaning or cooking to take care of children
Not really the reasoan why is that females are build to delivery the baby. Females have the body parts to give birth to a baby. It is the way Females are formed.
Chat with our AI personalities
Because men don't have babies. Only women have the parts to have babies, while men have the parts to fertilize the eggs and start pregnancy. In fact, the word woman is a shortened form of "womb man."
Religious answer:
Because Eve told Adam to eat the apple. That put shame on women and God decided to curse all women because of Eve.