A cloistered nun has stunned her mother superior and sisters after giving birth to a baby boy after complaining of severe stomach pains.

The sister, who belongs to an order in Macerata, in the eastern Italian region of Le Marche, claimed to have no idea she was pregnant when she was rushed to hospital in agony, after which she gave birth, the Daily Mail reports.

The South American nun, who arrived at the convent in June, when it is supposed she was already pregnant, was taken to the emergency department of 'Bartolomeo Eustachio' di San Severino Marche by her fellow sisters.

Doctors quickly unravelled the cause of the mysterious ailment.

The baby was born healthy but remains in hospital to undergo more checks, while the nun's convent has expressed an interest in taking care of him.

The case bears a striking similarity to that of a 33-year-old Salvadorean nun in Italy, who gave birth to a baby boy last year, whom she named after Pope Francis.

She told her social worker she did not feel guilty and would raise the child saying: 'I am so happy. 'He is a gift from God. I feel more of a mother than a nun.'

In 2011 a Congolese nun in an Italian order gave birth to a baby girl after being raped by a priest.

She gave up the baby for adoption but after being refused re-entry to the convent changed her mind and recovered the child.