The rapper, whose real name is Ben Haggerty, shared the news on Instagram.
"Tricia is pregnant, and today we are going to find out the gender of our child," Macklemore said in the video, posing next to a cake and pink and blue balloons alongside Davis and their 2-year-old daughter Sloane Ava Simone.
Macklemore, 34, and Davis were married in summer 2015, with the musician sharing that they had welcomed their daughter about two months prior.