Ultimately, the sending off of Sunderland captain Lee Cattermole - the fourth time he'd been sent-off in his career - proved costly for the Black Cats who still added a second goal despite being a man down.
Darren Bent gave the hosts an early lead from the penalty spot before Cattermole, after two yellow cards, became the first player to be dismissed in the Premier League this season.
Birmingham full-back Steve Carr looped a header into his own net early in the second half but the Blues hit back through Scott Dann's header 13 minutes from time before Liam Ridgewell's goal ensured the points were shared late on.
Sunderland manager Steve Bruce blasted referee Anthony Taylor claiming he was "out of his depth".
However, Bruce insisted he had no complaints about Cattermole's second yellow card, when the midfielder brought down Lee Bowyer from behind.