Trimethoprim-sulfonamide combination therapy in early pregnancy

One of my patients presented with bacteriuria early in her pregnancy. Urine culture was positive for Escherichia coli. I would like to prescribe a trimethoprim-sulfamethoxazole combination because it worked well for her in the past. What is known about the safety of this medication during early pregnancy?

Evidence-based studies report an association between trimethoprim-sulfonamide combinations in early pregnancy and several major malformations, such as neural tube defects and cardiovascular defects. If clinically possible, physicians are advised to use alternative antimicrobial medications for treatment of urinary tract infections during early pregnancy.