An active bolster for an automotive vehicle has an inner wall and an outer wall joined around a substantially closed perimeter to form an inflatable bladder. An inflator couples an inflation gas into the inflatable bladder in response to a crash event of the vehicle. The inner wall has an inner vessel region with a substantially-planar portion and an outer pleated region with a plurality of circumferential pleats, wherein each pleat has an inward edge and an outward edge. Adjacent pleats are continuous so that the inward edge of an outer pleat is shared as the outward edge of an inner pleat. The pleat edges have a stepped spacing from the outer wall that progressively decreases from an innermost edge to an outermost outward edge, whereby adjacent pleats unfold during inflation such that an inner pleat is unfolding with a substantially uniform pressure when an outer pleat begins to unfold.