3
The antibiotics -- trimethoprim-sulfamethoxazole (Bactrim) and nitrofurantoin (Macrobid) -- have been linked to a small risk for birth defects in pregnant women when given in the first trimester.

Source: MedMD
http://securenewsmiles.com/uncategorized/pregnant-women-getting-uti-meds-linked-to-defects/