According to the Rite of Baptism # 9 “To bring out the paschal character of baptism, it is recommended that the sacrament be celebrated during the Easter Vigil or on Sunday, when the Church commemorates the Lord’s resurrection. On Sunday, baptism may be celebrated even during Mass, so that the entire community may be present and the necessary relationship between baptism and Eucharist may be clearly seen...”
Although baptism of infants is not strictly forbidden during Lent something may be lost from the celebration, particularly when it takes place at Mass, since it is the scripture of the day that must be used for proclamation and for the homily. In addition, the Circular Letter states that “it is not fitting that Baptisms and Confirmations be celebrated” on Palm Sunday of the Passion of the Lord through Holy Thursday. {#27}
Lent is that season of the Liturgical Year when parishes spend much time preparing the elect for their initiation at the Easter Vigil by helping them become aware of how God wishes to cleanse them from all sin they have committed. It is also the time for preparing the faithful for their reconciliation so that all can come ready for the renewal of their baptismal commitment at the Easter celebration. Lent then, is the time to prepare for baptism and the renewal of baptism not necessarily to celebrate baptism.
Of course, in case of necessity, infants may be baptized during Lent, but it is more suitable that infant baptism be deferred until Easter.