The Influence of Prenatal DES Exposure on the Associations of Reproductive Factors and Osteoporosis.
Included in this study were 5,573 women who participated in the NCIDES Follow-up Study between 1994 and 2006. Data on reproductive history and medical conditions were collected on the first follow-up questionnaire in 1994 and subsequently on the 1997, 2001, and 2006 questionnaires.
The results of the study showed that women who had fewer than 25 years of menstruation (between the start of menstrual cycles and menopause) had a higher incidence of osteoporosis when compared with women who menstruated for 35 years or more. The association of years of menstruation with osteoporosis was shown observed in both DES-exposed and unexposed women, but was stronger among women who had not been prenatally exposed to DES.
The study's results support the hypothesis that total lifetime exposure to estrogens that occur naturally through a woman’s reproductive years protects against the development of osteoporosis. Furthermore, prenatal exposure to estrogen, in the form of DES, may reduce this protection, although we do not yet know how.