The pope baptised 34 infants during in a ceremony that lasted more than two hours at the Vatican on Sunday and told their mothers to feel free to breastfeed.
He told women taking part in the service not to be afraid of breastfeeding their children in the chapel, describing the act as "the language of love".
In an short, improvised homily, the pope said: "If they start performing a concert [by crying], or if they are uncomfortable or too warm or don't feel at ease or are hungry, breastfeed them.
"Don't be afraid, feed them, because this too is the language of love."
During the ceremony that lasted more than two hours, Francis baptised 18 girls and 16 boys, including two pairs of twins.
The Argentine has made similar comments in past ceremonies, including a baptism service in January 2017.
Television pictures showed at least one mother bottle-feeding her child.
Women still face harassment for breastfeeding in public in some countries.
The papal baptism is a yearly event restricted to children of employees of the Vatican or the diocese of Rome. Francis is also bishop of the Italian capital.
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