"[She's] told people she's going to name the baby Ace!" the source told Us Weekly. Simpson, 32, is already mom to 10-month-old daughter Maxwell. The singer hasn't yet revealed how she and Johnson, 33, decided upon the name, however.
Just last year, Simpson revealed that Maxwell's unique moniker came about as a tribute to both her family and her NFL player fiancé's.
Maxwell is Johnson's middle name as well as his grandmother's surname, and Drew is Simpson's mother Tina's maiden name.
"It's nothing shocking and nothing you'll have to add to the dictionary," the bubbly mother-to-be told Elle last year prior to Maxwell's birth and name reveal. "Still, when people hear it they'll know …why."
Simpson and Johnson first confirmed their second pregnancy via Twitter on Christmas day. And the expectant parents couldn't be more thrilled to expand their brood.
"Motherhood is a dream," Simpson told Katie Couric back in September. "It really is absolutely amazing."