If the firstborn child is a male, on the thirty-first day after birth a ritual takes place, known as Pidyon haben (redemption of the firstborn). The ritual dates back to the times when the firstborn had to be dedicated to God and perform service in the Temple of Jerusalem. The father "redeems" the son by handing five coins to a Kohen, that is, a descendant of a priestly family.
The rites of brit milah (circumcision) and pidyon haben take place only for male children; no similar ceremonies are provided for girls. In recent years, new traditions have developed the custom of celebrating the birth of a daughter with a celebration called Simchat Bat. In some families, the moment of giving a name to the daughter is also celebrated.
Source: "Per conoscere l'ebraismo" by Daniel Taub