Why do women get yeast infections..?

Fungal infections: Infections from fungi or overgrowth of yeast can occur in many parts of the body. The warm moist areas, like a woman's vagina, are the environments that promote growth and can lead to symptoms.

Yeast: Yeast infections are due to a fungus called Candida which is normally found in the vagina. However, if there is a lack of healthy vaginal bacteria it can lead to overgrowth of yeast. Some causes of overgrowth: antibiotics, ^ estrogen (pregnancy or some birth control pills), malfunctioning immune system, diabetes mellitus as well as friction against vaginal tissues (intercourse) & douching.

Normal flora...: Most cases of yeast infection are caused by overgrowth of normal yeast (candida) in the vagina. When an imbalance occurs, such as when the normal acidity of the vagina changes or when hormonal balance changes, yeast can multiply and build up. When this happens, symptoms of an infection may happen. Symptoms include itching and cheesy discharge. Less commonly, yeasts can be spread sexually.