The Daily Telegraph said Perry made the comment while speaking as part of a panel before an audience of more than 250 people at the duchess' former school.
"I think Kate Middleton is pregnant -- and that would be good for the economy," the Telegraph reported Perry said during a discussion of the impact the Olympics will have on the U.K. economy.
Royal observer Ingrid Seward told the newspaper Perry's remarks about the duchess are "very unhelpful."
"She would have no insider knowledge," Seward said. "It will be the best-kept secret of all time. There is no way they would want people to know before it was appropriate. Historically, there has always been speculation about this sort of thing, and, of course, you cannot stop people saying what they want. I should think the Duke and Duchess of Cambridge are probably pretty used to it, but also pretty fed up with it."
William and Kate married in a lavish London ceremony in April 2011. Their spokesman declined to comment on Perry's remarks.
Gal Gadot cast as Wonder Woman for 'Batman vs. Superman'
Couple mistakenly served bag of cash at McDonald's drive-thru