Birth is a stage of the reproductive cycle where a baby is born. In a lot of animals, this is usually through the mother's vagina. Birth in this manner is a natural process of most animals, not just humans. Sometimes, babies have to be born in a different way, especially if there is a problem with the mother or the baby; they can be born by something called a caesarian section. This is an operation where the baby is removed directly from the uterus through the abdominal wall. In some creatures, like reptiles, birds, and some fish, babies are born when they hatch from an Egg.