The DIY SOS host, 51, already has three older children but is expecting a baby boy this summer with his new wife, 26-year-old Jessica.
Jessica, who married Nick in Rome in September 2012, told Hello! Magazine: "Giving birth is a very physical process and I don't want him to see me in that vulnerable state. I prefer a little bit of smoke and mirrors."
The star said he was perfectly happy to follow his wife's wishes.
He said: "If Jess wanted me there, then of course I would be there, but I certainly don't feel offended that she doesn't. I'll be right outside, so I'll still be one of the first to hold our son.
"Men will tell you that they want to be at the birth but it's because they think they ought to be.
"Admitting that you're not going to be there provokes the most extraordinary reaction, as if it's an abdication of responsibility, but the fact is, it was only in the Sixties and Seventies that men started to be there at births.
"There's a huge amount of guilt, fear and worry on a man's behalf when their partner gives birth, along with a feeling of complete uselessness, so I'm more than happy to take Jess's lead on this."
The presenter also said he was relaxed about becoming a father again late in life.
He said: "Earlier it did hit me, 'When he's 16, I'll be 67. Blimey!' But I'm a bit of a Peter Pan in spirit and physically I keep myself pretty fit.
"Jess has already been trying to extend my life by reducing the number of pork pies and bacon sandwiches I eat and although I still smoke, I've cut down a lot.