Welcome to the world, Maxwell!

Jessica Simpson gave birth to a baby girl, Maxwell Drew Johnson, in L.A. Tuesday morning, Us Weekly can confirm. This is her first child with fiance Eric Johnson. "Eric and I are elated to announce the birth of our baby Maxwell Drew Johnson 9 lbs. 13 oz. 21 3/4," Simpson wrote on her website Tuesday. ""We are so grateful for all of the love, support and prayers we have received. This has been the greatest experience of our lives!"

According to a source, little Maxwell (she takes her middle name from her maternal grandmother, Tina Simpson, whose maiden name is Drew) weighed in a 9 lbs. 13 ounces. "Mother and baby are doing just fine," the source tells Us.

After just six months of dating, Simpson, 31, and Johnson, 32, got engaged in November 2010. The pair — who have yet to set a wedding date — had planned to hold off on making it official until after their baby's arrival. Rushing down the aisle isn't a priority for the star and her former NFL player beau, anyway; during a March appearance on Jimmy Kimmel's show, Simpson told the host that Johnson "feels like my husband already."

The Texas native was previously married to Nick Lachey from 2002 until their separation in 2005. (The duo famously documented their life together for MTV's hit reality show, Newlyweds.)

Following her divorce from Lachey, the Dukes of Hazzard actress dated Dallas Cowboys quarterback Tony Romo from 2007 to 2009.

In 2011, both Lachey and Romo tied the knot with their current flames; Romo's wife, Candace Crawford, gave birth to a baby boy Hawkins on April 9, and Lachey's spouse, Vanessa Lachey, is currently expecting the couple's first child.

Simpson first shared her own happy pregnancy news with the world on Twitter last Halloween.

Tweeting a photo of her wrapped in a mummy costume, she wrote, "It's true! I am going to be a mummy!"

Since then, the Fashion Star mentor and Johnson have been counting down the days 'til their little one's arrival. In December, Simpson opened up to Us Weekly about her excitement for "mummy"-hood.

"Eric and I love each other so much, and knowing that I love this baby inside of me is so amazing — I love it so much and I haven't even met them yet," Simpson gushed. "I can't imagine how much love we'll have for it once it finally comes!"

As her due date approached, the bubbly, uninhibited singer spoke candidly about the not-so-pretty parts of pregnancy, dishing on her strange cravings (buttered Pop Tarts!) and embarrassing physical traits ("I just started calling myself Swamp Ass," Simpson told Jay Leno of sweating through her maternity Spanx.)

Among the most outrageous? During a March interview on Jimmy Kimmel Live, Simpson made even seasoned comedian Kimmel blush when she admitted, "I feel like I have a bowling ball sitting on my hoohah. Apparently I have a lot of amniotic fluid, so whenever my water breaks, it will be like a fire hydrant!"

And speaking to Ryan Seacrest in an appearance on his radio show last month, the fashion designer opened up about her third-trimester sex drive. "I am definitely 'feeling intimate,'" Simpson told the host. "I'm kind of unstoppable right now. The Big O is, like, the biggest O ever!"

Source: US Weekly