"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," Nick Lachey said.
The couple married last July after dating for several years.
Lachey's ex-wife, singer-actress Jessica Simpson, is also pregnant with her first child. She is engaged to former NFL player Eric Johnson.