Diethylstilbestrol (DES) is a medication prescribed in the United States between 1948 and 1971 to prevent miscarriage or premature delivery. It is no longer prescribed because it was found to cause various medical problems in the children of the women who used it.

Daughters born to women who took DES while pregnant have a slightly higher risk of developing:

• Abnormal cervical cells that cause an abnormal Pap test.
• Cancer of the cervix or vagina.
• Structural problems in their reproductive organs, such as a T-shaped uterus or a weakened cervix, which can cause infertility and a higher risk of preterm labor.

Sons born to women who took DES while pregnant have a slightly higher risk of abnormalities of the scrotum and decreased sperm counts.