Rumours of a new arrival for the Manchester United footballer and his wife of less than a year have been circulating for over a week, but Mrs Rooney has now confirmed that the baby is due in October.
The 23-year-old wrote in her OK! magazine column: "It's true - I'm pregnant. It's the most brilliant news and, along with marrying Wayne, the best thing that's ever happened to me.
"Wayne is over the moon and so excited and I just know he'll be a great father.
"It's something we both wanted and we feel incredibly lucky and happy.
"The only sad thing is that the news leaked out before either of us or our families really wanted it to.
"Pregnancy is a miracle, but it's still the early stages. I really want to be able to keep as quiet and calm as possible for the sake of our baby."
She said that the couple - who are jointly worth £30million - did not yet know the sex of their child, adding: "We really don't mind as long as he or she is healthy and grows up happy."
She also confirmed she will continue to work - she has various magazine columns, a fragrance, jewellery and watches range, a fitness DVD and various advertising contracts.
She said: "There's a long way to go and in the meantime I'll be carrying on working, in between doing whatever is necessary for the pregnancy. Fingers crossed it's going to be a wonderful year!"
She also said that she will still consider adopting children in the future, following in the footsteps of fellow celebrities Angelina Jolie and Madonna.
She said: "Adoption does appeal to me because my little sister was adopted, but I think we'd like a family of our own first.
"Maybe we'd consider it after that."
