"ROUND 2....." she captioned a picture on Instagram of herself showing off her growing belly.
Prinsloo and Levine are already parents to daughter Dusty Rose, who turns one year old Sept. 21. Sources told People the couple are "so happy" to expand their family.
"Adam and Behati are so happy to be adding another baby to their family," an insider said. "They're amazing parents and their loved ones are thrilled for them."
"I think the fact that you could love a person more than you thought," the star told the magazine.
"I love Adam, and when you get married and fall in love with someone, you think that there's no greater love than that love," she explained.
"And then you have a baby, and it's just next-level love."