The Cincinnati offense spotted Bailey (1-2) a four-run lead in the first inning. He allowed five hits and struck out two and didn't walk a batter in a seven-inning outing.
The Reds got to Cubs starter Chris Volstad (0-2) for seven hits and six runs -- five earned -- in five innings as Chicago lost its sixth straight game.
Drew Stubbs had three hits and knocked in three runs for the Reds.
He scored the first run in the four-run Cincinnati first. Chris Heisey delivered a two-run single for the big hit of the rally.
Chicago scored two unearned runs -- after a Heisey error -- in the third but Stubbs made the score 6-2 with a two-run double in the fourth. Bailey got an RBI in the sixth with a fielder's choice that made the score 7-3.
Stubbs added an eighth inning RBI single and Jay Bruce scored on Todd Frazier's two-out triple in the ninth.