Leviticus 12:7-8
Then he shall offer it before the LORD and make atonement for her, and she shall be cleansed from the flow of her blood. This is the law for her who bears a child, whether a male or a female.
'But if she cannot afford a lamb, then she shall take two turtledoves or two young pigeons, the one for a burnt offering and the other for a sin offering; and the priest shall make atonement for her, and she will be clean.'"