Nicole Richie offers to give Jessica Simpson her kids

Jessica Simpson says it will be "amazing" to see herself "with a waistline" when she watches herself on the premiere of NBC's new reality show, "Fashion Star," adding that she feels like "a big blob."

Photos:

Halloween costumes of celebrities (2011)

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The 31-year-old pregnant singer, who has her own clothing lines, serves as a mentor to aspiring fashion designers on the series, which debuts on March 13 at 9:30 p.m. ET and was filmed months ago.

"I wasn't pregnant when we shot it," Simpson told Us Weekly magazine.! "It wil l be amazing to see myself with a waistline. I'll be like a big blob sitting on the couch watching myself thin."

Simpson's baby bump is prominent. She has not announced a due date but is expected to give birth in the spring. The singer confirmed on October 31, 2011 that she and fiance Eric Johnson, 31, are expecting their first child by posted a photo that sees her dressed as a mummy. The two began dating in May 2010 and announced the following November, after he finalized his divorce from his first wife, that they are engaged. No wedding date has been announced.

On "Fashion Star," the newbie designers will compete for buyers like H&M and Macy's to get their designs on the market. The show is hosted by supermodel Elle Macpherson and also features Nicole Richie as another mentor. The 30-year-old mother of two, who also has her own clothing line, recently extended an offer to Simpson to help her with her pregnancy.

"I offered [Jessica] to take my kids up until she has hers," Richie, who is known for her sense of humor, told the television show "Access Hollywood Live." "That didn't really work. The offer still stands because she hasn't had her kids yet. So, if she wants to take them, go ahead. No problem!"

Both Simpson and Richie are no strangers to reality television. Simpson co-starred with then-husband Nick Lachey on the MTV series "Newlyweds: Nick and Jessica", which documented their married life together before their ! divorce in 2006. In 2010, she appeared in the short-lived VH1 reality show "Jessica Simpson: The Price of Beauty."

Richie and Paris Hilton starred in the reality show "The Simple Life," which aired between 2003 and 2007. Richie has also served as a guest judge on "Project Runway."

Simpson told Us Weekly that she has not bought maternity clothes, preferring to wear clothes that come in bigger sizes. She had announced in January that she plans to launch a maternity line.

Her past collections of apparel, perfume and other products, which are marketed to young women, have raked in about $1 billion in sales.

The singer also launched her own line of diamond jewelry with Zales and teamed up with celebrity aesthetician Nerida Joy to launch BeautyMint, an online portal that sells anti-aging skincare.

(Pictured above: Left: Jessica Simpson appears in a promotional video for NBC's "Fashion Star." / Jessica Simpson poses with her fiance Eric Johnson at the 25th Annual Footwear News Achievement Awards at The Museum of Modern Art in New York on Nov. 29, 2011.)

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