Objectives: to evaluate the drug prescriptions for pregnant women in the Legal Amazon during prenatal care. Methods: this is a pharmacoepidemiological, descriptive, retrospective and cross-sectional study. Medical records included sociodemographic variables, prenatal care, most frequent pharmacological classes prescribed, risk classification of drugs and possible drug-drug interactions among pregnant women. Results: a total of 159 records from pregnant women, enrolled in the Unified Health System were used. Most pregnant women began prenatal consultations in the first trimester of pregnancy (53.3%) whereas most of the drugs were prescribed in the second gestational trimester (55.5%). The most used pharmacological classes, classified according to the National List of Essential Drugs were: antianemic preparations (52.9%), vitamins (12.5%) and analgesic (10.6%). According to the risk classification, the highest prevalence of prescribed drugs belongs to category A (46.8%), followed by category C (28.9%), category B (20.0%) and category D (4.3%). Eight possible drug-drug interactions were found, being considered with mild severity, and six classified with moderate risk. Conclusions: the results demonstrate a lack of information regarding prescription drugs for pregnant women and this may endanger maternal and fetal health. It is essential that medical records be an effective therapeutic tool, which should be read, analyzed and reviewed in order to ensure effective and safe medical treatment.