Why do I get a yeast infection a week before each period?

PH changes. The pH of the vagina can change for a variety of reasons. To prevent yeast infections and bacterial overgrowths as a result, take a good probiotic daily. Natren makes gy-na-tren, which my patients really like. Read more at: http://www.Drfinke.Com/2011/08/11/bacteria-and-your-body-its-a-good-thing/.
Don't know. 1 in 10 women get yeast infections over and over - usually about the same time each month during the menstrual cycle. We do not know why women get the yeast infections over and over, but we can treat and suppress to prevent the recurrences.