Vanessa and Nick Lachey

Vanessa and Nick Lachey

Nick Lachey hopes Vanessa Lachey doesn't go into labour over Christmas.

The former 98 Degrees singer's wife is set to give birth to their second child, a baby girl, in late December or early January, and admits he doesn't want the tot to arrive too early "from a selfish standpoint," as he loves the festive season.

He said: "[I'd] love to see it not happen in the holidays, but some things are out of our control!"

Asked when Vanessa is officially due, he said: "It's anybody's guess."

The heartthrob, 41, and Vanessa, 34, celebrated their joint birthday at Disneyland on Sunday (09.11.14) in order to focus all of their attention on their two-year-old son, Camden, as they are worried his unborn sister will "steal his thunder" once she arrives.

The 'What's Left Of Me' hitmaker told E! News: "We kind of wanted to do something special like that for him before his little sister arrives on the scene and steals his thunder."

Nick thinks Camden is excited to become a big brother, but doesn't think he fully understands what is happening.

He said: "We've definitely gone over the fact that, 'Hey, baby sister is in mommy's belly,' and he'll kiss the belly, so I think he understands what baby sister means and that that's happening, but I think the truth test is when she arrives and all the attention's not just on him! We'll see how he reacts at that point!"