The Championship leaders displayed great resilience as Luton appeared to be heading for their first away win in eight games following goals from their two strikers, Rowan Vine and Warren Feeney.
Luton always battled bravely despite the sickening blow of losing Markus Heikkinen with a broken leg early in the second half.
Birmingham, beaten 3-2 at Luton in October, were below form on the night but never gave up to earn a rather lucky point as the Hatters could have run out impressive winners on the night as they were generally the more dangerous side.
Vine, on loan from Portsmouth, was outstanding and notched his 13th goal of the season to demonstrate his value to the Hatters.
Birmingham huffed and puffed for long spells and were indebted to Gary McSheffrey scoring their opening goal to relieve the pressure following some desperate defensive play to shut out the threat of Vine and Feeney, who scored his first League goal of the season when he put Luton ahead for the first time.
Luton hardly operated like a team which had been beaten in their previous seven away games. The reason was that unlike many visiting teams to St Andrew's this season they were not content just to defend in the hope of collecting a point.
This refreshing approach was certainly an eye-opener and put Birmingham out of their stride to such an extent that they found themselves on the back-foot in the early stages.
It was in this spell that the danger of Vine and Feeney was troublesome to an anxious Birmingham that was far from secure. Radhi Jaidi was particularly fortunate not to concede a penalty with a desperate late lunge on Richard Langley.
In another innocent looking attack, Luton were unlucky not to go ahead. A hopeful cross from the left was headed goalwards by Vine and Maik Taylor could only stand and watch the ball hit the post and bounce to Feeney who headed weakly into the grateful arms of the Birmingham goalkeeper.
Birmingham, in very sharp contrast, were untidy in most aspects of their performance and hardly played like runaway leaders of the Championship.
There was a definite lack of drive in midfield in the combined absence of Damien Johnson and Stephen Clemence who have been the back-bone of Birmingham's dramatic revival over the last couple of months.
Typically, Birmingham turned the game into their favour with a swiftly executed move in the 31st minute which gave McSheffrey his 14th goal of the season.
In pouring rain Seb Larsson played the ball to the over-lapping Stephen Kelly who quickly found Nicklas Bendtner. The young Dane played a back-heeler to Cameron Jerome who crossed to the far post where McSheffrey's first effort bounced back to the former Coventry player off Kevin Foley to score at the second attempt.
But Birmingham's defence was badly at fault in the 43rd minute when they failed to clear Langley's poor free-kick. The ball was knocked to the unmarked Vine to slot home the equaliser with as low, angled shot.
Luton's performance was a revelation but they suffered as setback when they lost Heikkinen with a broken right leg.
Birmingham, however, struggled to get on top in the heavy, swirling rain as Luton, encouraged by their small band of travelling fans, strived to snatch a surprise win.
Their second goal came in the 77th minute following a smartly executed move. A defence-splitting pass from Sol Davis found Feeney and the Northern Ireland international turned and smashed a low angled shot past Taylor.
But Birmingham snatched a point out of the fire with a last desperate attack which resulted in Danns, who had missed from close range a couple of minutes earlier, slotting home the equaliser following a long cross from Mathew Sadler.