Objective: To identify and classify, according to the risk, the antimicrobials prescribed to pregnant women assisted by the National Program of Prenatal and Postpartum Follow-up in a municipality of Rio Grande do Sul. Methods: Analytical and retrospective cross-sectional study conducted in 2011 based on the registers of 87 pregnant women assisted in 2010 using an instrument with questions about the dispensed drugs. The prescribed antimicrobials were identified and classified as topical and systemic use and according to the risk of using it during pregnancy. Data were analyzed using SPSS 15.0. Results: The pregnant women had a mean age of 28.01 years and attended 5.3 consultations. There was an average prescription of 6.52 drugs/pregnant woman. Of the 568 drugs prescribed, 85 (14.96%) had an antimicrobial activity, 29 (34.1%) were for topical use and 56 (65.9%) for systemic use, and 46 (52.9%) pregnant women received at least one antimicrobial. There were 13 different products with a prevalence of antifungals of gynecological / topical use, 16 (18.82%), 30 (35.3%) were prescribed in the first trimester of pregnancy, 30 (35.3%) in the second and 25 (29.4%) in the third trimester. According to the classification of the risk to the fetus, nine (61.54%) antimicrobials belonged to the B category and four (30.77%) to the C category. Conclusion: It was verified the prescription of antimicrobials for systemic use and B category risk for pregnancy to 52.9% of pregnant women in prenatal follow-up in the place where the study took place. Miconazole and metronidazole vaginal cream, cephalexin 500 mg, azithromycin 500 mg and amoxicillin 500 mg were the most prescribed drugs.