The couple - who married last July - will welcome the baby into the world late summer and are ''overwhelmed'' at the prospect of becoming parents.
Co-hosting 'Live! With Kelly' this morning (05.03.12), Nick confirmed: ''I've had a chance to do a lot of great things in my career and my life but this is the one thing that, more than any other, I look forward to. The fact that it's actually here, it's overwhelming.''
Though they haven't found out the sex of the baby yet, Nick says they ''definitely'' will and have already started discussing names.
He said: ''We definitely want to know [the sex]. I can't take the knowledge that someone out there knows, but I don't know. It's like watching a sports game on TiVo.
''If it's a girl, I think it might be Sophia. If it's a boy, I'm not sure. Colin John Lachey [has always been a favourite]. Call him C.J. for short. C.J. Lachey.''
Nick revealed the 'Total Wipeout' host has been experiencing some cravings since conceiving.
He explained: ''She loves Mexican food. She could eat a burrito every day of the week.''