Reproductive and hormone-related outcomes in women whose mothers were exposed in utero to diethylstilbestrol (DES): A report from the US National Cancer Institute DES Third Generation Study.

BACKGROUND: Animal studies suggest that prenatal exposure to diethylstilbestrol (DES) causes epigenetic alterations in primordial germ cells that affect the next generation, but human studies are sparse.

METHODS: We assessed hormonally mediated outcomes in third generation women whose mothers were prenatally DES-exposed and unexposed.

RESULTS: Compared to the unexposed, DES-exposed third generation women had an increased risk of irregular menses and amenorrhea; the respective prevalence ratios and 95% confidence intervals (CI) in follow-up data were 1.32 (95% CI: 1.10, 1.60) and 1.26 (95% CI: 1.06, 1.49); associations were more apparent in third generation women whose prenatally DES-exposed mothers were affected by vaginal epithelial changes. The follow-up data also indicated an association with preterm delivery (relative risk (RR): 1.54; 95% CI: 1.35, 1.75).

CONCLUSION: DES third generation women may have an increased risk of irregular menstrual cycles, amenorrhea, and preterm delivery, consistent with inter-generational effects of endocrine disrupting chemical exposure in humans.