Michael Phelps and his fiancée Nicole Johnson have becomes parents for the first time! The Olympic swimmer and the former Miss California star welcomed their son on Thursday.
A couple of days later Michael shared a photo of the new family on Instagram, revealing the details of his baby's name and birth.
"Welcome Boomer Robert Phelps into the world!!!" he wrote. "Born 5-5-2016 at 7:21 pm!!! Healthy and happy!!! Best feeling I have ever felt in my life!!!"
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Michael Phelps and Nicole Johnson became parents on Thursday evening
The gold medallist went on to add that Nicole and baby Boomer are both healthy.
The professional black-and-white picture showed Michael, 30, cradling his sleeping baby in his arms as Nicole gazes lovingly at her fiancé and her first child.
Nicole, who will celebrate her first Mother's Day on Sunday, also shared a close-up snap of her son, showing her baby snuggled in a blanket that had been gifted from a friend. She wrote: "He's been laying in it since coming home. Goodnight & thank you for all the well wishes!!"
The swimmer shared his first photo of baby Boomer
In the lead-up to the birth, both Michael and Nicole kept fans updated with the new mum's pregnancy. One week ago Nicole shared a picture of her large baby bump, writing: "Can't believe I'm #36weeks today! #BabyP will be here in no time!!"
The couple decided to find out the sex of their baby in November and shared their exciting news with their fans. The pregnancy announcement came just a few months after Michael popped the question. However the couple won't be marrying until after the upcoming Rio 2016 Olympics.
Michael popped the question to Nicole last year
Michael, who is the most decorated Olympian of all time, checked into a facility and received treatment after he was arrested in September 2014 for the second time for DUI. He has vowed not to drink before the Olympics this summer.
The athlete has won a record 18 gold and 22 overall medals over the past three Olympics.