BIGGEST Loser trainers Michelle Bridges and Steve "Commando" Willis are expecting their first child together.

The couple confirmed the news on social media this morning.

On Instagram, 44-year-old fitness guru Bridges wrote:

"We're so happy to announce our special news.

"The well wishes and love we have received already are overwhelming and beautiful. Thank you so much. Michelle and Steve."

The couple also appear on the cover of Who magazine, sharing their excitement that "we're having a baby" and revealing that Bridges is now more than four months pregnant.

It will be the first child for the couple who began dating two years ago, after working together on The Biggest Loser since 2007.

Bridges was still married to her husband of nine years, Bill Moore, when the relationship started while Willis was also in a long-term relationship, with Froso the mother of his two youngest children.

The Commando has three children aged, six, three, and15, from two previous relationships.