Diethylstilbestrol (DES) is a synthetic form of the hormone estrogen that was first developed in the 1930s. It was prescribed to pregnant women to prevent complications such as miscarriages and premature births. However, it was later discovered that DES did not provide the intended benefits and could cause serious health issues for both mothers and their children. Research revealed that daughters exposed to DES in utero faced an increased risk of certain cancers, reproductive problems, and other health issues. As a result, the use of diethylstilbestrol in pregnancy was discontinued in the 1970s, and it is now recognized as a significant example of the importance of drug safety in pregnancy.