Girls good night everyone, we're almost 8 months pregnant, our daughter…

Girls good night everyone, we're almost 8 months pregnant, our daughter has been constipated for 3 days now ? She used to go potty several times a day before that. I don't want to put her on laxatives?? Could something be given from food to make her poop? We eat very little (mashed potatoes, vegetables, fruits) ?? Please tell us what to do ??