Substitute Noel Hunt scored the only goal of the game as Reading ended Birmingham's six-game unbeaten run at the Madejski this afternoon.
The Irish forward scored with his first touch of the game, nodding home Jobi McAnuff's centre.
Just before the breakthrough, Reading defender Alex Pearce almost diverted into his own net, as the ball hit the post and stayed out.
Brian McDermott's Royals jump three places to 14th while Birmingham, who still have three games in hand on most teams in the division because of their European commitments, are now 13th.
