The nun was rushed to a local hospital after experiencing several abdominal pains. An ultrasound scan revealed she was expecting a full-term baby boy, who was delivered by doctors during a natural birth.
"The baby is one of God's creatures and we have the utmost respect for human life. Pope Francis himself has recalled, that human errors aside, the dignity of the individual must be respected," said local parish priest Fabrizio Borrello.
"The nun will take care of her baby," he added.
All the other nuns at the convent were also unaware of the pregnancy and were "shocked" at the birth which was the talking point of Rieti, he said.
Doctors and the local health authority declined to comment.