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Bella Santorum, the youngest daughter of Rick Santorum has returned to the hospital.

"Rick and his wife Karen have taken their daughter Bella to the hospital," said Santorum spokesman Hogan Gidley in a written statement. "The family requests prayers and privacy as Bella works her way to recovery."

Bella Santorum suffers from Trisomy 18, a rare, but serious genetic condition Trisomy 18, which kills about 90 percent of children before or during birth. Bella has defied those odds and is three years old. She was also admitted to the hospital in January with pneumonia and Santorum briefly suspended campaigning. But according to Santorum, Bella had a "miraculous turnaround" in January.

There is not currently any indication what sent Bella to the hospital now.

The former Pennsylvania senator often talks about his daughter on the campaign trail. He says Bella did have multiple hospital visits her first year, including an incident so serious that Karen, a former neo-natal nurse, was able to intervene and perform CPR on Bella and rush her to the hospital in time.

The Santorums also tell the story of when Bella was first born, because of the gravity of her condition, they would have birthday parties daily, then weekly for Bella as she got better, to celebrate her life.

Read more about Trisomy 18.

Watch this ABC report about Bella's earlier trip to the hospital and her recovery from that bout with pneumonia: