Prenatal Exposure to Stilbestrol

Abstract

The effects of prenatal exposure to diethylstilbestrol were studied by a prospective cohort investigation of 110 exposed and 82 unexposed females. The general health characteristics of mothers and daughters in both groups were similar. Among the exposed, there were striking benign alterations of the genital tract, which included transverse ridges (22 per cent), abnormal vaginal mucosa (56 per cent), and biopsy-proved adenosis (35 per cent). Among the unexposed there were no ridges and one case of vaginal mucosal abnormality including adenosis (p < 0.0001). Abnormal cervical epithelium occurred in almost all exposed subjects but in only half the unexposed (p < 0.0001). The incidence of vaginal adenosis was highest when diethylstilbestrol was begun in early pregnancy. It was not detected when treatment was initiated in the 18th week or later. Oral contraceptive use and prior pregnancy were associated with less adenosis and erosion, respectively (p <0.05). No cases of cancer were observed. (N Engl J Med 292:334–339, 1975)