Michael Phelps' wife Nicole is pregnant, expecting baby no. 2

Michael and Nicole Phelps are expecting their second child together!

The 32-year-old Olympic swimmer announced the happy news on Instagram. "Number 2 on the way!!!! So excited!!" he wrote alongside a sweet pic of Nicole and their 15-month-old son, Boomer. "Wonder if it's a boy or a girl??"

Nicole, a model and 2010 Miss California USA, shared the same pic to her account writing, "Lil man's going to be a Big Brother!!!"

And Boomer, who has his own Instagram account, shared a photo of him clapping his hands together. "So excited to see what mama is having!!" the caption read. "Do I get to have a brother or a sister?!?"

The decorated sportsman wed his longtime love, Nicole, 31, in an intimate five-person ceremony in their backyard in June 2016, one month after their son was born.

Afterwards, Nicole revealed to People that nobody outside their families knew about their nuptials.

The next month, Michael competed in his fifth and final Olympics in Rio de Janeiro, Brazil, where he won his record-breaking 23rd gold medal -- before announcing his retirement from the sport.

"One of the coolest things about being a father going into Rio is that our firstborn has the chance to see my last race ever," he said at the time.  

And then, in October, the sweet couple followed up with a larger wedding with 50 of their closest friends in Cabo San Lucas, Mexico.