In this Mishnah, we’ll list the fourth category, continuing from the previous Mishnah: a firstborn son who is not a Bechor L'Nachalah (for the laws of inheritance) or a Bechor (firstborn) for Pidyon HaBen (redemption of the firstborn son). How could that be? The Mishnah says: a firstborn son who was delivered by C-section. That would be a baby who doesn’t come out of his mother the natural way, but is surgically removed through a cut in her stomach. The naturally born son after him and the firstborn son delivered by C-section are both not a Bechor: neither is a Bechor for the laws of inheritance or for Pidyon HaBen.
The first son is not a Bechor because only a child who was born naturally could be a Bechor. But in any case, when the Torah tells us that a person is a Bechor, it uses a word that describes giving birth. The Torah tells us, “It was born to him.” So what we understand from here is that it has to be a son who was born naturally. That could be a Bechor (firstborn). A son who was born through a C-section cannot be a Bechor for the laws of inheritance. When it comes to Pidyon HaBen, only natural birth opens up the mother’s womb. So logically, he wouldn’t be a Peter Rechem (opener of the womb). The Torah, for inheritance, says the words V'yaldu Lo (it was born to him), and for Pidyon HaBen, he has to actually be Peter Rechem. He has to emerge from the mother’s womb naturally.
So in this case, the first son is not a Bechor for either Pidyon HaBen or inheritance, and the second son is not a Bechor either, because he is not the firstborn of either his mother or his father. The second son is not a first child to his father that his father would mourn, because he would mourn the first son, who was delivered by C-section. Therefore, for the laws of inheritance, the second child is not a Bechor. And even though the second son was the one who broke through the mother’s womb, he is not considered to be a Pidyon HaBen, because he is not her first child. The Torah holds over here that, in order to be a Bechor for Pidyon HaBen, you have to meet two criteria. Number one, you have to be the mother’s first child, and you have to be the one who opened up the mother’s womb. Here, this second child did not accomplish that.
Another opinion: The first son is a Bechor for inheritance, even though he wasn’t born naturally. Natural birth is not a requirement for the laws of inheritance. The second is a Bechor for Pidyon HaBen, even though he is not a Bechor for inheritance and is not the firstborn; he is the one who opened his mother’s womb. According to Rabbi Shimon, that is enough to make him a Bechor for Pidyon HaBen: he opened the mother’s womb, even though he is not the first child. Rabbi Shimon understands that, for the laws of inheritance, this is learned from a Pasuk (verse): delivery by C-section is considered to be birth. So a baby born in this way can be considered to be a Bechor in terms of inheritance, even though the child wasn’t born the natural way. He also holds that a son who opens his mother’s womb is a Bechor in terms of Pidyon HaBen, even if he is not her first child.