Jessica Simpson Reveals Bikini-Clad Baby Bump Photo

Jessica Simpson is flaunting her pregnancy belly.On Monday, the soon-to-be mom-of-three took to [...]

Jessica Simpson is flaunting her pregnancy belly.

On Monday, the soon-to-be mom-of-three took to Twitter to show off her third trimester body, posing for the camera in a patterned bikini and sunglasses with her hand resting on her growing baby bump.

"Jess-tation," she captioned the photo.

The expectant mother and her husband, Eric Johnson, announced in September that their family of four would be growing to a family of five sometime this spring, making 5-year-old son Ace Knute and 6-year-old daughter Maxwell "Maxi" Drew big siblings. Their little one on the way, a baby girl, will be named Birdie, Simpson revealed in photos from her baby shower.

While no stranger to being pregnant, the "I Think I'm in Love With You" singer's third pregnancy has been anything but easy.

In January, Simpson showed off her extremely swollen feet, and updated fans just a month later about her struggles with sciatica pain and bronchitis.

"After a month of sciatica pain, followed by 3 weeks of Bronchitis, I figured since my feet fit in my sneaks today I needed to walk out a lot of anxiety!!" she wrote.

Earlier this month, Simpson revealed that she had been hospitalized just weeks ahead of her due date for bronchitis for the fourth time in two months.

"After a week in the hospital for bronchitis (my fourth time in 2 months), I'm finally home! Coughing with Birdie has been a crazy painful journey. I am slowly getting healthier every day. Baby girl was monitored and is doing amazing!" she wrote. "I am on my way to healthy and counting down the days to see her sweet smile. Sending love and prayers to all the mothers who are going or have gone through this. OUCH."

Despite the difficult pregnancy, Simpson is "doing great," according to her sister Ashlee Simpson, and she even took inspiration from her latest pregnancy to help launch the latest line in her of her fashion brand, launching limited edition pieces as part of her Jessica Simpson Maternity line.

"We launched Jessica Simpson Maternity right after my pregnancy with Maxwell, so it's been an exciting experience to re-look at the line six years later and bump things up a little with this capsule," she told PEOPLE. "We added some elevated pieces that I get to wear now during this pregnancy."