Over the past several decades, the public has grown increasingly aware of the problems drugs and alcohol can cause in pregnancy. Research has linked alcohol, illicit drugs -- and even some over-the-counter medications -- to birth defects and slowed development in infants.
The American Congress of Obstetricians and Gynecologists (ACOG) advises pregnant women to avoid all medications and drugs as much as possible, but to check with their doctor before discontinuing any prescription medications.
Some of the biggest developmental offenders are marijuana, heroin, cocaine, Ecstasy and other amphetamines. Heavy use of these drugs is associated with low birth weight, preterm birth, congenital problems, and learning and developmental disabilities.
Alcohol is perhaps the most commonly abused substance in pregnancy. In moderate to large amounts it can cause fetal alcohol syndrome -- a condition that may involve reduced baby size or weight as well as learning and developmental problems -- and raise the risk of premature delivery.