During the mass and ceremony under the chapel's famed frescos, Francis baptized 26 babies: 13 girls and 13 boys.

In his brief unscripted remarks, the pope repeated his advice from previous years, telling mothers to feel free to breast-feed their babies if they cried or were hungry.

"My wish is that you will be able to raise these children in faith, and that the greatest heritage they receive from you is faith. And just one piece of advice, when a child cries because he is hungry, I tell the mothers, if your child is hungry, feel free to feed them here," he said.

The pope has used similar words to make mothers feel at ease before.

Baptism is the sacrament at which infants or converts are initiated into the Christian faith. Francis poured water on the foreheads of the infants as part of the ritual.

The Sistine Chapel, which Michelangelo painted in the 16th century, is the room where cardinals elect popes in secret conclaves. Francis was elected the first non-European pope in nearly 1,300 years there on March 13, 2013.