The hormone diethylstilbestrol, commonly known as DES, is known to cause a rare vaginal cancer in young women exposed to DES as fetuses, but the long-term health risks for these women was unknown until recently. A study published in the October 6th issue of the New England Journal of Medicine found that beyond vaginal cancer, DES likely causes a range of lifelong reproductive-health problems for women exposed as infants.These women have much higher-than-average rates of infertility, miscarriage, premature delivery, stillborn delivery and early menopause. Women exposed to DES in their mothers’ wombs also have above-average rates of breast and uterine cancer. The exact number of women exposed to DES as infants is unknown, but is likely between 3 and 10 million. The effects of DES on the granddaughters of women who took DES during pregnancy are also not known, but laboratory-animal studies show signs of third-generation effects.