Wikipedia
`Aqīqah, "Aqeeqa", "Aqeeqah" ([Arabic]: عقيقة) is the Islamic tradition of the sacrifice of an animal on the occasion of a child's birth. It is widely performed by Muslims and it is considered sunnah to slaughter one sheep for the baby girl and two sheep for the baby boy. But in Shia Islam, there is not any difference between the baby girl and baby boy. Aqiqah is a Sunnat al Mu'akkadah (confirmed sunnah). If the guardian of the child is capable of slaughtering two sheep for a baby boy and one sheep for a female child, he should do it. Muhammed said : “A baby is being pledged for his Aqiqah, sacrifice is made for him on the seventh day, his head is shaved, and a name is given him". If one cannot slaughter on the seventh day, one may slaughter on the fourteenth day or on the twenty-first day. If one is not capable of doing so, then one may slaughter any time before the puberty of the child.