A healthy vagina has a balance of different bacteria and yeast. If a bacteria or yeast start to increase, throwing the vaginal flora off balance, then you’ll get a vaginal infection like a yeast infection or bacterial vaginosis. This vaginal flora can be thrown off balance by a weakened immune system, the use antibiotics or other medications, pregnancy, your menstruation or diabetes. Irritating ingredients like perfume and plastics found in products that come in close contact with your vagina can also cause infection.