Objective: Assessment of the knowledge that future mothers have about the importance of their oral health and future oral health of their newborn. Methods: An observational cross-sectional study was designed in which the participants were pregnant women and mothers of newborns living in the city of Viseu, Portugal. The self-administered questionnaires were distributed to a final sample of 68 participants. The objective of this questionnaire was to assess the oral hygiene and the level of oral health of pregnant women and the importance attributed to them, taking into account the implications of oral health in the newborn. Results: It was observed that the participants had satisfactory oral health habits and had some knowledge about the oral health of the newborn, however, in certain fundamental parameters they had a significant lack of knowledge. Most pregnant and mothers of newborns rated their oral health as good (30.9%) and very good (38.2%). However, 14.7% consider that their oral health was bad, which is a concerning issue considering that the sample were young pregnant and mothers of a newborn. Conclusions: We find that there is a need to educate the population about oral healthcare during pregnancy, postpartum care, and also oral health of the newborns. In this way, we are contributing to a better future for the oral health of the community. However, further studies should be performed in order to better understand the oral health behaviours of mothers to better define preventive strategies in the field of oral health.