Seal got Heidi Klum pregnant a couple of months ago. Now he's revealed the sex of his wife's fourth baby - a girl! - on a taping of The Oprah Winfrey Show.

"She can't keep a secret," said Seal, who confirmed they're expecting a girl, and who first announced they were pregnant again at a NYC concert in April.

In Klum's first interview about her pregnancy, she revealed that she was hoping for a girl: "We'd be happy with either, but it would be a lie if I said we all weren't hoping for a little girl - especially Leni, she would love to have a little sister."

Either way, she's gonna have some gorgeous genes ...

Seal and Heidi Klum in January (left), and after the birth of Johan.

The Project Runway host and Seal are currently raising a serious brood: Leni, 5 (whose dad is Italian businessman Flavio Briatore), Henry, 3, and Johan, 2.

The couple is celebrating their fourth anniversary this Sunday.

"We're going to get married again," Seal said. "This is going to be our fourth anniversary. The fifth time, and I'm not quite sure what the theme is."

"You know what my wife's like," he added. "She's always got a trick up her sleeve, but it's going to be a good get-together, you know, lots of friends."