Fury announced the arrival of his sixth child with his wife Paris on Sunday.Baby Athena was put into intensive care at Alder Hey Children's Hospital in Liverpool, but Fury announced the following day that she was "doing fantastic" and had been taken off the ventilator.
However, he posted a photo of his new daughter on his Instagram on Tuesday night, saying: "Baby Athena is back on ICU, please keep her in your prayers".
The boxer has now set up a fundraising page to support Ronald McDonald House at Alder Hey Children's Hospital, and almost £32,000 has already been raised.
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Fury is donating two signed WBC belts as part of the fundraiser, which he will personally sign and hand over to the winners.
You can go online to donate and be in with a chance of winning here.
Fury has thanked everyone for their pledges, saying: "Massive thanks to everyone who has helped, u are amazing".
The couple announced that Paris was pregnant in February, and revealed they were expecting a daughter.
They have been married since 2009 and are already parents to daughters Venezuela, 11, and three-year-old Valencia Amber, and sons Prince John James, eight, Prince Tyson II, four, and one-year-old Prince Adonis.