Many studies show a relationship between milk intake and conception. A team of researchers in the United States and Finland report that in areas where milk consumption is highest, women tend to experience the sharpest age-related falloff in infertility. Milk has also been linked to menstrual cycle irregularities, early menopause, pre-menstrual syndrome, and recurrent vaginal yeast infections. Galactose, a sugar found only in milk, is harmful to ovarian function and to the developing, unfertilized egg. Some doctors also recommend avoiding all soft cheese products because the production process doesn't involve pasteurization. This results in the presence of the bacteria lysteria, which can cause miscarriage.