Jessica Simpson Shows Off Slim Body on Fashion Star Set Before Second Pregnancy Announcement

USMagazine, Thursday, January 24, 2013, 3:00pm (PST)

During the seven months between her two pregnancies, Jessica Simpson was hard at work on the set of NBC's Fashion Star. In a sneak peek from season 2 of the NBC series -- exclusive to Us Weekly -- the new mom shows off her slim post-baby body after welcoming daughter Maxwell in May 2012.

Simpson, 32, serves with John Varvatos and Nicole Richie as mentors to contestants on the reality competition show. Louise Roe has also replaced Elle Macpherson as host for season 2, which premieres on March 8 at 8 p.m. on NBC.

PHOTOS: Jessica Simpson's body evolution

After shedding 70 pounds with the help of Weight Watchers following her first pregnancy, Simpson flaunted her lean legs and slim waist on set in a short coral dress, black pumps and skinny black belt. In another shot, Simpson showed off her cleavage in a long black dress with a plunging neckline.

During filming, a source tells Us that Simpson would often bring daughter Maxwell with her to set -- leaving her little girl with Grandma Tina Simpson when the cameras rolled. "Maxwell is a total mommy's girl," the source explained. "She just wants to be held by Jessica."

PHOTOS: Meet Maxwell Drew!

Added a show source: "Jess is really cute with Max. The baby is adorable and never disruptive."

Soon she'll have two tykes underfoot! Us Weekly exclusively revealed in November that Simpson is expecting her second child with fiance Eric Johnson, and the star confirmed the news herself on Christmas Day. During an interview on The Tonight Show on Jan. 15, Simpson admitted she was "extremely shocked" to find out she was pregnant again.

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"Because I was going through a lot of hormonal changes, trying to get back to the old, vibrant Jessica," she explained. "You know, it was kind of like a one-night stand. And it happened, all over again!"

The second-time mom-to-be is also set to try her hand at non-reality TV in an NBC sitcom pilot inspired by her own life. In a statement Jan. 15, Simpson said, "I often find myself thinking that no one could ever make up the things that actually happen in my life, so between the real life elements and a great team of writers, I think we'll have people laughing."

This article originally appeared on Usmagazine.com: Jessica Simpson Shows Off Slim Body on Fashion Star Set Before Second Pregnancy Announcement