Pregnant woman injured after car crosses four lanes and crashes into bushes

Dashcam has captured the moment an erratic driver speared across the Kwinana Freeway and rolled in bushes.

The Holden Barina was filmed tailgating before it clipped a barrier and careered across four lanes.

It hit another car, hurting a pregnant woman.

She was taken to hospital with stomach pain.

The crash happened just after 8.30am on Saturday, blocking the Leach Highway off-ramp.

The 24-year-old driver was trapped inside the wreckage for more than an hour and suffered serious injuries.

No charges have been laid.