Jessica Simpson arrives at her 32nd birthday bash at The Beverly Hills Hotel with baby Maxwell on July 10, 2012. Credit:

Jessica Simpson was surrounded by those who love her most on July 10, her 32nd birthday.

The Fashion Star mentor arrived at the Polo Lounge in L.A. around 12:30 with her fiance, Eric Johnson, 32, and their 10-week old daughter, Maxwell Drew. The new mom smiled as she cooed over her little girl in the backseat of her future husband's car.

The trio were also joined by Jessica's sister, Ashlee Simpson, 27, and her BFF, Cacee Cobb, 34. According to a source, the group popped champagne and dined outdoors before serenading Jessica with a rendition of "Happy Birthday."

"There was a lot of laughter coming from the table and everyone looked very joyous," the source tells Us Weekly. (See more photos at X17.)

Since becoming a first-time parent May 1, Simpson is relishing every moment of motherhood. "Everyone is marveling at what a natural Jessica is," a family pal recently told Us. "She was born to be a mom."

When she's not tending to her little girl, Simpson has been busy hitting the gym in an effort to lose weight; as Us first reported in November, Simpson has signed on for a $4 million Weight Watchers deal.

"The cool thing about the program is that it focuses on healthy habits for the long-term (and I can still indulge in my guilty pleasures every now and then, too)," she explained via Facebook on May 30. "I have actually gotten a group of friends together who are going to be doing it with me."