"Why did I do it? Because I thought pregnancy was the most beautiful thing ever, and I wanted to express that in a way it's never been expressed before," Rinna, 33, told CBS This Morning.
Billed as the "mother of all pictorials," Rinna's 10-page photo spread is also a first for Playboy. Rinna appears to the first pregnant actress to bare all, following the lead of actress Demi Moore who was partially nude in her now-famous 1990 Vanity Fair cover.
"Not only does it take pregnancy to a new level, it takes Playboy to a new level," said the Medford, Ore., native who plays vixenish Taylor McBride in popular television series. "It shows where we are in society for Playboy to show a woman pregnant and naked."
Rinna's husband of 16 months, actor Harry Hamlin - best known as one of the stars of the long-running TV drama L.A. Law - appeared in the spread with her.
"He's very supportive; he thinks it's great; he thinks it's beautiful," said Rinna, a former high-school cheerleader. She admits a lot of thought went into the decision to pose nude. "It wasn't an easy decision; we had to talk it through, definitely," she said.
Rinna's 10-year career has included the role of Billie Reed Brady for three years on the soap opera Days of Our Lives and roles in numerous TV movies including Close To Danger, Vanished and Lies Before Kisses. She also made guest appearances on the TV series Baywatch, House Rules, and The Hogan Family.
Despite all this, she said she is awed by her Playboy cover.
" That's me over there on the cover of Playboy, oh my God," she said. "I'm proud of it. I will always be proud of it. I will always be very happy with that decision that I made."