The 29-year-old Victoria's Secret model shared the good news by posting a nude photo of herself flaunting her small baby bump.
"This is not a #throwbackthursday this is now!" she captioned the picture. "So happy to share with you that we are expecting."
In what appears to be a professional photo, Kroes strikes a pose for the camera while standing completely naked. The model covers her breasts with one hand and holds her burgeoning bump with the other.
The Dutch model and her Dutch DJ husband, who wed in November 2010, are already parents to son Phyllon, 3.