A police official says the bomber struck Monday while she was lining up with other women to be searched by female security guards at a checkpoint on the outskirts of the Shiite neighborhood of Shaab.
He says about 117 people have been wounded. He says 18 women and 12 children are among the dead.
A hospital official is also confirming the casualties. Both officials spoke on condition of anonymity because they are not authorized to talk to the media.
Hundreds of thousands of pilgrims are going to Karbala to mark a revered Shiite day.
