Are prunes safe to eat during pregnancy? I don't want to eat them if they can cause contractions or induce labor.

I've been so constipated the past couple weeks it's unreal. Two weeks ago my water broke at 20 weeks and I will be 22 weeks in two more days. I've been dilated half a centimeter the past couple weeks also. In 13 more days I will be admitted to the hospital and start steroids and I'm hoping to death I can make it. I've been taking colace everyday and drink like a gallon of water but my stools are still not soft and tmi gross, I have been having to manually dig it out which I've never had to do before it's embarrassing, but I don't want to strain so that's why I do that. I've heard about eating prunes daily but I'm scared to eat them if they can cause me to have contractions or induce labor. Does anyone know?