BOSTON (CBS) – A special party was held at Tufts Medical Center Thursday to celebrate the first birthday of very special twin boys who were born several weeks apart.

The nurses and doctors who cared for them and their mother were invited to the celebration.

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Last February, Lindalva da Silva, pregnant with fraternal twins, went into labor 16 weeks early. She gave birth to Alexandre Antunes, who was whisked off to the neonatal intensive care unit (NICU).

But in a rare twist, doctors at Tufts Medical Center were able to keep the second twin growing inside the womb.

“One twin was in a hurry to get out and one twin said, ‘Hey, I’m going to hang out.’ And it was great. It helped their medical course because one wasn’t born so early,” Pamela Hallaran, a NICU nurse at Floating Hospital for Children at Tufts Medical Center, who cared for the twins, explained.

Ronaldo Antunes arrived 24 days later, on March 26, making today his one year birthday. His twin already turned one earlier this month.

“One year later we are here celebrating,” said Ronaldo Antunes, the boys’ father. “It looks like it was yesterday. It’s unbelievable. Grateful to be here celebrating their first year,” Antunes adds.

Alexandre and Ronaldo Antunes were born 24 days apart in 2014. (WBZ-TV)

Alexandre and Ronaldo Antunes were born 24 days apart in 2014. (WBZ-TV)

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Delayed interval deliveries are exceptionally rare, says Dr. Jonathan Davis, Chief of Newborn Medicine at the Floating Hospital for Children at Tufts Medical Center.

“It’s the first time in my career I’ve seen it this successful,” he said. “I’ve seen it attempted a number of times and it was never quite successful, and in this case it made a huge difference.“

Both boys are doing remarkably well, a real gift to the nurses and doctors who cared for them.

“This makes my whole day,” said Davis. “When I can go to a 1 year birthday party and see these kids doing well, it really justifies all the time, energy and effort we put into it.”

“To see them go from being tiny and fighting for their lives,” says NICU nurse JoAnn Loiselle. ”To be thriving with what looks like no deficits is almost a miracle.”

The boys’ mother had a simple message of gratitude to the nurses and doctors who helped her and her babies.

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“Thank you, thank you,” says da Silva. “That’s the only word. Thank you so much.”

Dr. Mallika Marshall