Yes! Prantals have so much iron which messes up our bowel movement. It should stop after birth but could continue especially if your doctor still has you taking the prenatals.
Raisins should work hopefully. Also when you're on the toilet, elevating your feet should help. Placing a step stool underneath your feet or even the trash can. Are you taking prenatals? I went thru constipation during my pregnancy and it was the worst.