Pope Francis reportedly healed a three-month old infant who had a heart ailment during the pontiff's canonisation of John Paul II and John XXII in the Vatican last year.

The baby's mother Lynn Cassidy told news station KPNX that the family went to Vatican in April 2014 and had waited for hours in the rain at the barricade in St. Peter's Square to see the Pope.

When the Popemobile passed by, she said her husband Scott held their daughter Ave up in the air, and shortly, a secret service agent stopped and took their baby and held her up to the Pope who placed his hand on the baby's chest.

"The Pope asked my husband, 'How old is she? What's her name?' He told [the pope] 'she has two holes in her heart.' When we got home in May, we went back to the cardiologist for a check-up. One of the holes was completely closed and one was half the size," said Cassidy.

"It seems like it was really meant to happen... And it's as close to a miracle as we'll ever see, I'm sure," the mother said.

Cassidy said they believe "divine intervention" by the Pope healed Ave.

Now 20 months old, Ave has successfully undergone eye surgeries and received hearing aids, according to the family from Arizona.

Last March during a trip to Naples, Pope Francis was also credited with performing a miracle when he venerated a vial of blood belonging to the martyred Neapolitan patron St. Gennaro. The dry blood reportedly turned to liquid after the pontiff prayed over it and kissed it. The miracle was declared by the Archbishop of Naples, Crescenzio Sepe.

The head of the Roman Catholic Church flew to Philadelphia on Saturday to preside the World Meeting of Families. He will stay in Philadelphia until Sunday. One of his last scheduled events is a Mass for the World Meeting of Families before taking a flight back to Rome.

Earlier, Pope Francis held a mass at St. Patrick's Cathedral and at Madison Square Garden in New York City. He also attended the United Nations General Assembly.

A day earlier, he spoke before 11,000 people gathered on the South Lawn at the White House in Washington regarding the importance of defending religious freedom and taking care of the environment, according to the Christian Post.