Reading stretched their unbeaten run to five games in all competitions after being held by high-flying Birmingham.
Reading’s Ali Al-Habsi made an early save after Lukas Jutkiewicz had got on the end of David Cotterill’s free-kick.
Michael Morrison went close for Birmingham before Jutkiewicz was again thwarted by Al-Habsi in the first half.
Diego Fabbrini fired just wide for Birmingham in the 90th minute before team-mate David Davis missed the target in the second minute of stoppage-time.
The result means Birmingham drop a place to fifth in the Championship table, while Reading go up one spot to 10th.