In the Torah it says that G-d changed Abraham's name from Avram to Avraham at the time of his circumcision. In keeping with that tradition, a Jewish boy is given his Hebrew name at the time of his Brit Milah. Judaism places a great deal of significance on a child's Hebrew name. It is often customary to name the child after someone who led a righteous life so that the child will try to emulate that individual. Ashkenazic Jews often name their children after a dearly departed relative, while Sephardic Jews sometimes name their children in honour of living relatives. In the case of a someone who died at a young age, another name referring to life, or the name of a person who lived a full life is added.
The Hebrew naming of a baby girl should take place at the first occasion after the baby is born when the the father can be called to the Torah. At that time a special prayer is recited on behalf of the mother and the baby, and a Hebrew name is given to the child. The guidelines for naming a baby girl are the same as for naming a baby boy. [Rabbi Moshe Shulman]