What could be the cause of green urine?

Okay, so I'm 17 weeks pregnant, and last time i saw my midwife she said i have e coli in my urine, and put me on antibiotics to get rid of it. I had no symptoms. Now that i've started taking them, my urine has turned yellow/green (like a really bright colour). I also take my prenatals, which i have taken for 3 months already with no problem, but have recently started iodine supplements. Is the iodine or the antibiotics turning my pee green as a side effect, or should i see a doctor?