DES Study (DES)
The DES or diethylstilbestrol Study is a follow-up of the Chicago DES Cohort. This study was conducted to pursue hypotheses about the non-cancer health effects of prenatal estrogen exposure in adults as suggested by laboratory animal studies or clinical reports. Such health effects include allergy, infection and autoimmune diseases, cognitive function, male fertility, menstrual cycle function, onset of menopause and age of menarche in the daughters of prenatally-exposed women. Given the estrogen-like activity of several classes of environmental contaminants, the identification of risk in this highly-exposed DES group could suggest more specific hypotheses for the study of the presumably-weaker effects of environmental estrogens.
From 1950 through 1952, Dieckmann and his colleagues at Chicago Lying-in Hospital—part of the University of Chicago Hospitals and Health System (UCHHS)—tested the efficacy of DES in preventing complications during pregnancy in 1,600 women using a double-blind, placebo-controlled clinical trial. Women in the treatment group received gradually-increasing daily doses of DES from around the first prenatal visit until delivery. These doses were high: the average treated mother received more than 12 grams of DES during the course of pregnancy.
A total of 848 boys and 805 girls were born during the original clinical trial. When DES was identified in 1971 as a transplacental carcinogen in the daughters of clinical trial mothers, the University of Chicago attempted to trace all participants and their offspring. No further contact was made with the males born during the study until 1991, when the follow-up study was initiated. Wilcox and his group studied 494 sons (253 exposed and 241 unexposed) and 542 daughters (296 exposed and 246 unexposed).
Allen J. Wilcox, M.D., Ph.D.
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