The stage of prenatal growth After about the tenth week, the fetus should grow rapidly in weight and size. At this stage, certain drugs may damage organs that are still developing, such as the eyes, as well as the nervous system. Continuing drug use also increases the risk of miscarriage and premature delivery. But the greatest danger drugs pose at this stage is their potential to interfere with normal growth. Low-birthweight babies require special care and run a much higher risk of severe health problems or even death.
Some drugs can be especially harmful at the end of pregnancy.
They may make delivery more difficult or dangerous, or they may create health problems for the newborn baby. Alcohol Alcohol is one of the most dangerous drugs for pregnant women, especially in the early weeks. In the mother's body, alcohol breaks down chemically to a cell-damaging compound that is readily absorbed by the fetus. Heavy drinking during early pregnancy greatly increases the risk of a cluster of birth defects known as fetal alcohol syndrome. Heavy drinking in later pregnancy may also impede growth.