“We’re having a girl!” Simpson, 30, tells PEOPLE exclusively.
The mom-to-be — who PEOPLE confirmed in December was pregnant with her second child — was anxious to find out the sex of their little one on the way. “I like to know — I want to do the nursery,” she says.
According to the singer and actress, they found out that they were expecting this past Thanksgiving, which she calls “a cute, fun day.”
“I told him pretty early on,” Simpson says of breaking the news to her firstborn. “And he wanted to have a sister, so he’s really excited! He’s got a little brother. Now he’s going to have a little sister!”
As for what the mom is looking forward to most? “I’m just excited for the new addition,” she says.
— Jeff Nelson