Currently, periodontal disease during pregnancy is associated with gestational diabetes, low birth weight and preterm birth. This study was aimed to determine the difference in the level of knowledge about periodontal disease prevention, before and after applying a motivational educational intervention in pregnant women at a primary health care center. Quasi-experimental study in 180 pregnant women from a health center, during the period September to December 2022. The data collection technique was a questionnaire survey with satisfactory characteristics of validity and reliability. An educational intervention with a motivational approach was developed, which was validated in a preliminary pilot test. The Wilcoxon statistical test was used to compare knowledge before and after intervention, and the Chi-square test to assess the association between variables. The age and educational level that predominated were 21 to 30 years and complete secondary school, respectively. A significant difference was found between the level of knowledge before and after in pregnant women (P < 0.001). There was no association between the level of knowledge about periodontal disease prevention with age and educational level in pregnant women at the health center, before and after a motivational intervention (P?> 0.05). The motivational educational intervention managed to significantly improve the level of knowledge in pregnant women about the prevention of periodontal disease; however, it was not associated with age and educational level. © (2023), (University of Dicle). All Rights Reserved.