This report aims to compare the use of medication during pregnancy in Brazil according to socio-demographic variables in pregnant women who received prenatal care in Unified National Health System (SUS) facilities in six large cities. A structured questionnaire was applied to 5,564 pregnant women who attended prenatal care at SUS facilities, all of whom were participants in the Brazilian Study on Gestational Diabetes (1991-1995). The use of any type of medication presented a positive association with increases in schooling, age, and having a partner, and a negative association with an increase in the number of children. Multivitamin and digestive tract-related drug use showed a positive association with increased schooling and age and a negative association with increased number of children. The use of medication for anemia was negatively associated with increases in schooling and age. Use of multivitamins and GI drugs was associated with variables that characterize pregnant women with higher socioeconomic status, suggesting that medication during pregnancy is an expression of prenatal care.