Entertainment Tonight.

Jimmy Fallon revealed on Friday that the reason that he and his wife Nancy Juvonen Fallon kept her latest pregnancy a secret is because their baby girl Winnie Rose was actually born via surrogate.

The newly-named Tonight Show host -- who is set to take over for Jay Leno in 2014 -- broke the news to the Today show's Savannah Guthrie during an interview scheduled to air next week. "My wife and I had been trying for a while to have a baby," said Fallon, 38, who married Juvonen, 46, in 2007. "We tried a bunch of things. So we had a surrogate."

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Winnie Rose Fallon arrived on July 23, weighing 5 pounds 9 ounces.

Fallon added, "This time we just said we're not going to tell anybody. It'd be just more fun, if it's just private between me and my wife, and then we get to introduce her to everybody. When it happened, we were shocked... Who are we going to tell? Who's going to be mad at us?" he said, calling the whole experience "emotional."

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