Objective To evaluate pregnant women's knowledge and perception of oral practices as well as their relationship with periodontal disease. Methods The project was developed in 27 units of the Family Health Strategy in the city of Picos, State of Piauí, Brazil, whose service prioritized providing the first dental appointment for pregnant women. A questionnaire was applied to 302 pregnant women, and a calibrated examiner (Kappa=0.96) performed the intraoral exam (CPI). Results the disease was present in 90.7% of them, although 96.4% had been to the dentist once, the majority have not seen a dentist during pregnancy, either because they feared the treatment would harm the baby, or lack of perceiving the need for doing so. Among those that had seen a dentist, did so because of pain or due to routine dental appointments. (19.9%). The belief that pregnancy could cause oral problems was mentioned by 39.7%, however, the majority (98.3%) stated they had received no guidance in this period, a fact which was shown to be associated with periodontal disease (p=0.0003). Conclusion It was concluded that there had been disease prevalence in the group, becoming persistent throughout pregnancy and also that the women presented many oral health care doubts during their gestational period.