Sam Gallagher capitalised on a defensive mix-up to earn Birmingham a point after Ben Davies had put Preston ahead in the first half.
North End have now won just one of their last six matches, including four draws to sit four points off the play-off spots. Birmingham remain inside the Championship relegation zone, but have lost only once in their last four league games.
Sam Gallagher had an opening for Birmingham after some smart build-up play in the fifth minute, but goalkeeper Chris Maxwell diverted his low strike from 12 yards wide with his left foot.
And Sam Gallagher was almost in again five minutes later, but failed to make enough contact with a header from six yards from Jeremie Boga’s cross from the left. It was all Birmingham in the opening stages, but against the run of play Preston took the lead after 17 minutes.
Paul Gallagher’s free-kick was only headed across his own goal by Marc Roberts and Davies was on hand to tap in his first Preston goal at the far post.
Birmingham, who have not won at Deepdale since 2001, had the chance to test Maxwell in the Preston goal after 58 minutes with a free-kick in a central position from 20 yards, but Jacques Maghoma dragged his effort wide.
And Blues threatened again three minutes later as David Davis picked out Gallagher from the left, but the striker could not keep his header down from 12 yards.
Birmingham’s second-half pressure told after 63 minutes, however, with a helping hand from some calamitous Preston defending.
Paul Huntington lost the ball to Maghoma and, when Maxwell rushed from his goal to attempt to clear the danger, he was easily rounded and the ball was played to Gallagher who slotted into the unguarded net.
Preston had failed to register a shot on target other than Davies’ goal, but they did create an opening after 79 minutes as Louis Moult, making his debut, was picked out inside the area but looped his header wide of the far post.
Maghoma had Birmingham’s best chance for a winner in the 82nd minute as he was put in behind the Preston back four by Davis, but his tame effort was easily gathered by Maxwell.
Newcastle have been linked with a shock move for former Sunderland goalkeeper Simon Mignolet during the summer.