This sheet is about exposure to sulfamethoxazole-trimethoprim in pregnancy and while breastfeeding. This information is based on available published literature. It should not take the place of medical care and advice from your healthcare provider. What is sulfamethoxazole-trimethoprim (SMZ-TMP)? Sulfamethoxazole and trimethoprim (SMZ-TMP) are two medications that have been used together to treat bacterial infections including urinary tract infections (UTIs). They belong to a class of …