"You go through therapy and blame your parents – now all of a sudden you're a parent and there's no one to blame any more. Your child could blame you," he said, adding that he had worried whether or not he would be a good role model for his kids because he had never had to do anything for himself since being propelled into stardom at 16.
"I was calm at the beginning," he said, "Then I gave up smoking and, I don't know if it was because of the nicotine leaving my system, but I started to worry. There are all these concerns."
He revealed that he and his wife had interviewed a nanny - 'they're like the oracle of little baby people' - and had then chilled out a bit!
Robbie also told GQ of his love for his 33-year-old wife, saying:
"You know there's so much positive stuff going with the two of us; she's really kind and attentive and wants the best for people and wants to help them.
"Once I'd seen that in her, it made me feel good that she wanted to be with me, which must mean that I'm actually good, so I was like, well, let's cultivate this."
"I went all the way through my twenties thinking I was sentenced to a life of mental imprisonment but I'm in a better place now."