Why does the woman have to go through the pain of giving birth?

In Islam we are treated fairly and equally in a just manner. However, a woman is told that if her husband calls her then she has to answer, she has to asker permission to go out, she has to serve her husband and take care of him. Then if the husband need to fulfil his sexual desires she has to leave what she is doing and go to him. If the husband goes to sleep when he is angry because his wife did not let him touch her then the Angels curse the wife. Why? I mean the wife has to feel all this pain just to fulfil his desires? The man won't care because he doesn't feel the pain the woman goes through. He doesn't have to carry the baby for nine months then feel the pain of giving birth. What if the wife is scared of giving birth because of the pain? It's all fun and games for the men yet they are the ones that should not get upset? What about the pain women go through? Why don't the men give birth since they are made as the stronger ones? Since they are allowed to go out without a Mahram? So my question is why does the woman have to feel pain to have children but not the man?