Carey - who is expecting a baby boy and girl with Cannon - stripped off for Life & Style magazine earlier this month, and Nick said that she looked so good that they wanted to share the snaps with the world.
He told MTV News, 'I think the cover is beautiful. The way that happened - we weren't planning to put that out. It was an idea [where I said], 'You look beautiful. Let's take pictures'.
'It turned out to be so beautiful. We were like, 'The world has to see this'. I actually took some naked pictures too with her - hopefully those won't be on no magazine covers anytime soon.'
He added that Carey is doing well as she approaches the end of her pregnancy.
'She's doing amazingly right now,' he said. 'She's such a trooper to be carrying two human beings in her body and for her to have such high spirits and to be so understanding.
'It's just wonderful just to see her in all her aura and beauty, glow.'