I had a UTI early in preg., diagnosed about 12 weeks. U have more chance of having another if you've had one. However, UTI, as far as I know, don't cause preterm labor. If it advances into kidney infection, this can cause preterm labor, according to my preg. books. THis happened to my SIL. According to her, you'll know for sure if you have a kidney infection, much worse than UTI, with fever, etc. Since my first UTI, I've been drinking lots more, esp water. THis seems to help. I also have heard that cranberry juice is good for cleaning kidneys, as was mentioned.