The tonight show

Jessica Simpson wore a low-cut dress for an appearance on The Tonight Show yesterday. Fresh off an extended holiday vacation to Hawaii with her fiancé, Eric Johnson, their daughter, Maxwell, and a rotating cast of friends and family, Jess was ready to chat about her second pregnancy and her various work projects. One of those projects was announced yesterday morning — a Jessica Simpson scripted comedy is in the works at host Jay Leno's network, NBC.

Jessica was her usual funny candid self while talking with Jay about her expanding family. She said that she and Eric, who've been engaged for two years, "had two different wedding dates, but he keeps knocking me up! We're doing it very backwards. I'll just keep my legs crossed this time." As for their having two kids within two years, apparently it wasn't planned. Jessica admitted, "I was extremely shocked because I was going through a lot of hormonal changes, trying to get back to the old, vibrant Jessica. You know, it was kind of like a one-night stand. And it happened all over again!"

Megan Fox stopped by The Tonight Show last night to chat about her latest film, This Is 40. She wore a figure-flattering blue Roland Mouret dress that showed off her post-baby body. Megan gave birth to her baby boy, Noah Green, three months ago, and while chatting with Jay Leno last night, she jokingly shared concerns that Noah was not the average baby. "I was convinced that I was, like, maybe birthing a vampire baby like the one in Twilight — you know what happens to Bella, where she's in cold sweats all the time."

Megan also revealed that the last time she stopped by The Tonight Show, she was actually trying to hide her growing baby bump. "I was about two months pregnant. I was really sick." Fortunately, Megan made it through the rough patch and went on to describe the pregnancy as "perfect." Now the first-time mum, and stepmum to her husband Brian Austin Green's son Kassius, is enjoying motherhood and celebrating the release of her comedy with Leslie Mann and Paul Rudd.

Kristen Stewart opted for another round of bold prints and lots of leg-baring for her second Breaking Dawn Part 2 promo appearance last night on The Tonight Show. Her brightly hued Peter Pilotto Resort '13 number was an eye-catching choice, thanks to the dress's structural cut, thigh-high hem, and striking striped design. To complete her look, she wore classic black Christian Louboutin pumps and her favourite Cartier Juste un Clou bracelet. It seems, after only two promo stops, that Kristen is veering toward playful prints and edgier silhouettes. Lest we forget, she was also the first to wear — and might we add, wear really well — a checkered look from the Louis Vuitton Spring '13 runway for her Tokyo appearance. And, as the current face of Balenciaga's perfume Florabotanica, we have a feeling she's got some memorable ensembles on the way. Click through for an all-angles look at her latest — then, be sure to come back soon for more of our Breaking Dawn Part 2 style breakdown.

Kristen Stewart was smiley and happy as she stepped out in a colourful Peter Pilotto dress to chat with Jay Leno for The Tonight Show in LA on Monday evening. Kristen spoke to Jay about the final Twilight movies, Breaking Dawn Part 1 and Part 2, saying, "Popped one out — pretty concerned with that. Me and Edward are doing quite well; people keep trying to kill my baby. But I'm now super-spectacular, so I can take care of that, being a vampire." Kristen also touched on Breaking Dawn Part 2's twist ending: "Every time I see it or even think about it, I get giddy. It freaks me out . . . It's easy to skim over. But you can find the root of our little twist [in the book]." Kristen switched gears from her blockbuster franchise to promote her indie project On the Road over the weekend. Kristen premiered On the Road at the AFI Festival in LA on Saturday, and she was joined by boyfriend Robert Pattinson at that after party. While Kristen was chatting with Jay, Rob was elsewhere in town making his own appearance on Jimmy Kimmel's show.

Britney Spears was on The Tonight Show With Jay Leno on Monday night, sporting a cleavage-baring dress and her new bangs. The X Factor US judge was joined by her colleague Simon Cowell for the late-night visit. Britney told Jay that a "real charming phone call" from Simon convinced her to sign on for the series, and she also admitted that she's had a hard time getting used to being booed by the audience when she's tough on contestants, saying the heckling makes her "cringe."

Tomorrow night will be the start of The X Factor's live shows, which will feature performances from the remaining finalists. The reality competition has faced some ratings challenges in its second season, with The Voice US drawing a larger audience share. Despite it, Fox has announced that The X Factor will be back for a third season, and the show has also earned several People's Choice Awards nominations, including a spot in the running for this year's favourite competition show.

Miley Cyrus wore a unique ensemble for her Friday chat on The Tonight Show. She and host Jay Leno were together to talk about her small role on Two and a Half Men, but chat veered toward her eye-catching Anthony Vaccarello bustier and Moschino maxi skirt combo. She also chatted about her upcoming album and shared a sneak peek at one of her "backyard sessions" in which she tests out new music. The clip she previewed was special, since right after recording it, Liam Hemsworth proposed! Miley said, "That's one of Liam's favourite songs — he asked me to marry him 20 minutes later. So while I was singing it, I had no idea! He was looking at me funny! And then I knew."

It was a busy week for celebrities on Twitter as the stars shared exciting holiday photos from work and play. Ian Somerhalder visited The Tonight Show while No Doubt saluted Paul McCartney at the Kennedy Center Honors. Kathy Griffin and Katy Perry teamed up to perform for US troops and Jenna Dewan got a special surprise on her 30th birthday. Don't forget to follow PopSugar on Twitter for all the latest celeb news and photos!