The rapper has become firm friends with the pregnant pop star over the past few months, after Lily agreed to feature on his track 'Just Be Good to Green', and he admits it was getting hard for him not to tell people the news because of the amount of concerts Lily was cancelling.
He told BANG Showbiz: "It was hard. Everyone was asking me why she kept pulling out of gigs and all I could say was, 'Oh she's sick.' I'm so glad everyone knows now."
And the 26-year-old pop newcomer - who first met Lily after they were introduced on social networking site Facebook by mutual friends - has joked he is going to buy Lily's baby "a Rolex, like she got me".
Although he is happy for Lily and her boyfriend Sam Cooper, Green - real name Stephen Manderson - isn't ready to have kids of his own any time soon.
He said: "I wouldn't consider getting pregnant any time soon and I'm not thinking of getting anyone else pregnant either!"