Sliwinska gave birth to a baby boy whom she and her husband named Michael Alexander Mazo on Saturday, January 4, Peoplereported.
"We are extremely happy and in love with him. So far it's been the most amazing experience of my life," Sliwinska told People. "Even though I've been told how incredible it is to be a mom, I never imagined I would enjoy so much every minute spent with my little munchkin."
The couple announced they were expecting a baby in October. The 35-year-old Russian-born Mazo and the 32-year-old Polish-born Sliwinska got engaged in Fall 2006 and wed one year later. They've been together for a total of 13 years.
Mazo appeared on five seasons of Dancing with the Stars. He won the show's inaugural season with Kelly Monaco in 2005 and eventually left the series after its tenth season in 2010.
Sliwinska competed as a pro on the first 10 straight seasons of Dancing with the Stars. The highest she ever finished was second place with celebrity partner Jason Taylor in Season 6.