Although the couple did not reveal the name until after Boomer’s birth, Phelps had said previously that the couple selected the baby’s name ahead of time.
“It’s something we both agreed on. Thought it was different,” he said at a meet in Mesa, Ariz., in April.
At the same meet, Phelps reportedly sought parenting advice from fellow Olympian Dana Vollmer, who made her return to swimming last summer after giving birth to her first child.
“It will be good for him, like it is for me,” Vollmer said. “Michael and Nicole will be good parents.”
Phelps was training at altitude in Colorado Springs as recently as Wednesday, when he conducted a Facebook Live session from the pool deck at the Olympic Training Center, but flew home to Arizona ahead of Thursday’s birth.
The 22-time Olympic medalist had been scheduled to swim in Atlanta next weekend in what would have been one of his final preparation meets ahead of this summer’s U.S. Olympic Trials, but Phelps told organizers that he would be withdrawing in order to be in Arizona for the birth of his son.
With limited opportunities to compete before Trials, Phelps could potentially re-enter the meet or, instead, choose to participate in USA Swimming’s Pro Swim Series event in Charlotte the same weekend.