Objectives: The aim of the study was to evaluate whether the presence of the disease in pregnancy influences the effectiveness and safety of delivery preinduction with prostaglandins: misoprostol vaginal insert and dinoprostone vaginal gel., Material and Methods: This is aretrospective cohort study conducted of 560 pregnant women. The concomitant diseases mainly recorded were diabetes mellitus, hypertensive diseases, intrahepatic cholestasis of pregnancy, asthma, thrombocytopenia, and hypothyroidism. The primary study outcome was a successful vaginal delivery. The study above others evaluates the time from treatment implementation to the beginning of a labor and to a final delivery, the rate of Cesarean sections, and the presence of delivery complications., Results: Among women with a concomitant disease, Caesarean section was observed more frequently in the misoprostol group. In the dinoprostone group, mothers with the concomitant disease as compared to healthy mothers required more time to the delivery and to achieve the beginning of labor. There were no differences in postpartum complications regardless of the prostaglandins, comorbidities or mothers' age. Neonates of mothers ≥ 35 years old with concomitant disease had lower average Apgar scores., Conclusions: Our study showed that comorbidities seem to increase the caesarean section risk in the misoprostol preinduction group but in the dinoprostone group they prolong the time needed to achieve an active labour phase and a delivery.