Rumors that Crystal was pregnant first surfaced on Sunday, after he shared a snap of her holding a photo of the couple with Ne-Yo's hand on her belly and included the caption: "Surprise!!!!!!!!!!"
The R&B singer also has two children, daughter Madilyn and son Mason, from his previous engagement to Moynetta Shaw.
During an appearance on the reality show Atlanta Exes, Moynetta had previously stated that she had her tubes tied while she was with Ne-Yo.
He addressed that drama in a follow-up tweet on Monday by stating: "Clearing the air..I didn't force Mo to tie her tubes. Mutual decision. And the procedure is reversible. #SheCanHaveKids #FromTheHorsesMouth."