Jane Fonda (AP/Invision)

Kelly Rowland for ELLE.com (Courtesy of ELLE.com)

Christina Aguilera for V Magazine (Courtesy of Brian Bowen Smith/VMagazine.com)

Jenelle Evans (Courtesy of Instagram)

Kim Kardashian (Courtesy Of Karl Lagerfeld, Direction by Riccardo Tisci/ CRfashionbook)

Kim Zolciak (Courtesy of Instagram)

Elsa Pataky (Courtesy of Instagram)

Holly Madison (Courtesy of Instagram)

Shiri Appleby (Courtesy of Instagram)

Jessica Simpson snapped a photo of her second pregnancy while on vacation to Hawaii in December 2012. (Courtesy of Twitter)

Gisele Bündchen pregnant with baby Vivian Lake on vacation in Miami in November 2012. (FameFlynet)

Tori Spelling pregnant with baby Finn Davey (Courtesy of Torispelling.com)

Jenna Dewan-Tatum pregnant with her first child on vacation with husband Channing Tatum in St. Barts (FameFlynet)

Kate Middleton snapped in a photo in a bikini on vacation to Mustique with husband Prince William. (Courtes of Star Magazine)

Cacee Cobb pregnant with her first child. (FameFlynet)

Kim Kardashian pregnant with her first child on the cover of Us Weekly on the May 20, 2013 issue. (Courtesy of Us Weekly)

Jessica Simpson pregnant with Maxwell Drew on the cover of Elle for the April 2012 issue. (Courtesy of Elle)

Britney Spears pregnant with Jayden James on the cover of Harper's Bazaar on the August 2006 issue. (Courtesy of Harper's Bazaar)

Christina Aguilera on cover of the January 2008 issue of Marie Claire.

Mariah Carey pregnant with Moroccan Scott and Monroe on the cover of Life&Style magazine.

Demi Moore's controversial and groundbreaking cover of Vanity Fair of August, 1991. (Courtesy of Vanity Fair)

Nia Long pregnant with Kez Sunday Udoka on the cover of Ebony for the November 2011 issue. (Courtesy of Ebony magazine)

Claudia Schiffer pregnant with daughter Cosima on the cover of Vogue UK for the May 2010 issue. (Courtesy of Vogue UK)

Kendra Wilkinson (Getty)

Jessica Chastain (Getty)