Wikipedia has more:

In medieval Europe, the pelican was thought to be particularly attentive to her young, to the point of providing her own blood by wounding her own breast when no other food was available. As a result, the pelican became a symbol of the Passion of Jesus and of the Eucharist. The self-sacrificial aspect of the pelican was re-inforced by the widely-read mediaeval bestiaries. The device of “a pelican in her piety” or “a pelican vulning (from Latin vulno to wound) herself” was used in heraldry. Another version of the myth is that the pelican used to kill its young then resurrect them with its blood, again analogous to the sacrifice of Jesus. The symbol of the Irish Blood Transfusion Service is a pelican, and for most of its existence the headquarters of the service was located at Pelican House in Dublin, Ireland.

The emblems of both Corpus Christi College, Cambridge, Corpus Christi College, Oxford and the medical faculties of Charles University in Prague are pelicans, showing its use as a medieval Christian symbol (‘Corpus Christi’ means ‘body of Christ’).

Likewise a folktale from India says that a pelican killed her young by rough treatment but was then so contrite that she resurrected them with her own blood.

These legends may have arisen because pelicans look as if they are stabbing themselves as they often press their bill into their chest to fully empty their pouch. Other possibilities are that they often rest their bills on their breasts, and that the Dalmatian Pelican has a blood-red pouch in the early breeding season.