Christian Initiation
Where infant Baptism has become the form in which this sacrament is usually celebrated, it has become a single act encapsulating the preparatory stages of Christian initiation in a very abridged way. By its very nature infant Baptism requires a post-baptismal catechumenate. Not only is there a need for instruction after Baptism, but also for the necessary flowering of baptismal grace in personal growth. The catechism has its proper place here.
Source: Catechism of the Catholic Church (Vatican.va)