I am very prone to yeast infections and have to get something for my OB when I get them(usually after taking antibiotics) OTC meds dont work for me.. You should try taking Acidophilus or eating probiotic yoghurt on a daily basis to help prevent them? I found since started this I am not getting them as frequent.
Unfortunately some women are prone to recurrent yeast infections during pregnancy. Unless your doctor has told you specific OTC brands of yeast medication that are safe to use it is NOT adviseable to use OTC remedies as not all of them are safe. You really need to see you obgyn to get a prescription for something that can help knock this out instead of just making it become dormant for a short period of time. The last time I had a yeast infection during pregnancy my doctor prescribed somethign called Zazole (other brand name is Terazol and generic is terconazole) It knocked it out within a few days and I didn't have another problem with yeast infections for the rest of that pregnancy.
I am lucky enough to have not had this problem with any of my pregnancies but friends of mine have and they swear by this stuff sorry not sure of the name but i do know they got it from the health shop, hope this helps some what.