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A baby boy is thriving after doctors performed a rare heart surgery on him while he was still in his mother’s womb.

Mom Kristine Barry said the sound of her baby boy crying after he was born was music to her ears.

“The most amazing sound I’ve ever heard,” said Barry.

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Her son, Sebastian, arrived at Mount Sinai Hospital in Toronto in May. During her prenatal checkups, doctors discovered a severe congenital heart defect.

In order to fix the problems, doctors operated before Sebastian arrived. Otherwise, they would have just minutes to operate after his birth.

Sebastian underwent additional surgeries, including open-heart surgery, after he was born to make sure everything was functioning properly.

Now, two months later, Sebastian is a happy and healthy baby with a bright future.