Alcohol Effects

• Alcohol intake during pregnancy can cause fetal alcohol syndrome (FAS), a condition characterized by abnormal facial features, heart defects, slowed growth and cognitive impairment ranging from learning disabilities to mental retardation, according to the American Council for Drug Education.
  
  

Alcohol Abstinence

• While a moderate amount of alcohol during pregnancy is considered acceptable in some cultures, no safe level has been determined by the American College of Obstetricians and Gynecologists, so complete abstinence is the only way to ensure your baby won't be harmed.
  
  

Drug Effects

• According to Robert Needlman, M.D. on Dr. Spock's website, cigarettes, cocaine and marijuana can interfere with brain development and fetal growth.
  
  

Medications

• While illegal drugs are well-known dangers during pregnancy, many prescription and over-the-counter medications can harm a fetus as well. Only those medications prescribed or approved by your doctor should be taken.
  
  

No Safe Intake

• Some women believe that alcohol and drugs are safer in late pregnancy, when the baby is almost fully formed. However, alcohol and drugs are not safe at any stage of pregnancy.