Yeastrol Review Part-9 - Version 9.0 Yeast infection affects 75% women. It is different from other medical conditions even if the symptoms are the same. This infection needs to be treated at the earliest. Yeast infections usually affect adult females; hence it is important to get rid of it. Any fungus grows well in dark and moist area, hence yeast has a tendency to grow in the female reproductive organ. Yeast is already present in the reproductive organ's area of women in normal circumstances. Nearly 75% of women get a yeast infection at least once in their life time. Yeast infections happen once the yeast starts to multiply without any control. Usually this happens when a women's normal immune system is weakened. The antibiotics being used to battle any disease or treat any illness may be the reason for this.