Robb Dipple/Hilton Media Group

Christina Aguilera posed for pictures at the World Hunger Relief's "Pass the Red Cup" challenge in Los Angeles on Tuesday, and the 33-year-old starlet showed off her baby bump in a white dress and denim jacket. Lookin' good, Xtina!

Aguilera has served as a global spokesperson for WHR since 2009, and yesterday she tweeted, "Join me and #PassTheRedCup by donating $5 to feed 20 children for @yumbrands @WldHungerRelief." WHR benefits the U.N. World Food Programme), and Xtina recently spoke out about why this cause was so important to her.

"It's heartbreaking to me that in our social media driven, increasingly-connected world, nearly 850 million people go to bed hungry each night," she wrote in an article published on the Huffington Post. "And this includes far too many children. It's a subject so close to my heart and has been for a long time, being a mom."

On spending time at a refugee camp in Rwanda she added, "They told me how they escaped violence in the Democratic Republic of Congo. Their courage and hope for a better life was incredible. On my trip, I served food to kids who walk miles to and from school each day to receive a hot meal. I also went to Haiti after the earthquake hit a few years ago and saw its devastating effects on many families. Kids there were so happy just to get rice and beans from WFP."