The premature labour has been regarded as a highly problematic clinical event not only due to its relation with perinatal mortality but also in the light of the remote results of the prematurity. Evaluation of the influence of active periodontitis on a preterm delivery risk. Retrospective assessment of the preterm delivery risk in a group of pregnant women with clinically confirmed periodontitis and healthy otherwise was performed. Further risk assessment was stratified on a basis whether prophylactic measures against this dental pathology were introduced (n = 30 of women were treated). The control group consisted of 30 pregnant and healthy women. Patients with active periodontitis and having a prophylactic treatment had a 4-fold increase of a preterm delivery risk compared to those without this dental pathology. The risk was 12 times higher in the group with advanced changes and no treatment. According to the results, periodontitis should be regarded as a systemic disorder capable of affecting a pregnancy so prevention procedures should be introduced as soon as the problem is recognized. Such a procedure involving dental assessment in described population could significantly decrease the number of preterm deliveries.