Fetal alcohol syndrome (FAS) is a pattern of permanent physical, mental and behavioral abnormalities that can occur as the result of fetal exposure to alcohol. The damage of FAS is done while a fetus is still developing inside the uterus – when a woman consumes alcohol while pregnant. Alcohol consumed at any time during the course of a pregnancy can affect a fetus.

Within a week of conception, an embryo (fertilized egg at the early stages of development) attaches to the uterine wall, through which it will receive nutrients from the woman’s bloodstream. If there is alcohol in the woman’s bloodstream, it passes through the placenta (protective tissue) and into the fetus’ blood via its umbilical cord.

The first trimester (12 weeks) of pregnancy is a critical period of development. Early on, embryo cells multiply and begin to assume different, specific functions – a stage called differentiation – creating blood cells, kidney cells, nerve cells and more. This is a key developmental stage for facial features, heart and other organs, bones and the central nervous system (CNS). Exposure to alcohol at this stage can be particularly damaging to a fetus. Because the brain continues to develop throughout pregnancy, it may be harmed by exposure to alcohol at any time during the pregnancy.

Exactly how alcohol causes damage to the developing fetus is not clear. Tissue exposed to alcohol may fail to develop normally, may not develop in the appropriate location or may die – all of which can lead to the structural and functional birth defects of FAS. Which organs or systems are affected will depend on the fetal development taking place when alcohol exposure occurs.   

Not all fetuses exposed to alcohol develop birth defects. Heavy drinkers may produce healthy infants, and light to moderate drinkers can give birth to babies with FAS. The amount of alcohol that causes damage is unclear – and appears to vary from person to person. It can depend on the amount consumed, the regularity of consumption, as well as when during the course of a pregnancy alcohol consumption occurs. Women who are pregnant do not need to be heavy drinkers, or drink every day, to cause fetal damage.

FAS is a lifelong condition. Children with FAS display distinctive facial features, physical growth deficiencies and CNS problems. CNS abnormalities can range from mild learning disabilities to severe mental retardation. Mental retardation due to fetal alcohol exposure occurs more often than any other known cause (e.g., Down syndrome, spina bifida or muscular dystrophy).

FAS can lead to additional problems as children get older. These include:

• Incomplete education (e.g., as the result of suspension, expulsion, dropping out)
  
  
• Arrest, imprisonment
  
  
• Mental health disorders (e.g., attention deficit hyperactivity disorder, conduct disorder, depression)
  
  
• Substance abuse
  
  
• Inappropriate sexual behavior (e.g., inappropriate advances, touching)
  
  
• Unemployment
  
  
• Inability to live independently

The U.S. Department of Health and Human Services (Substance Abuse and Mental Health Services Association) estimates that 40,000 babies are born every year in the United States with some signs of prenatal exposure to alcohol.

Approximately 1,200 children are born with full-blown FAS, according to the American Academy of Family Physicians. The exact number of children considered to have FAS may vary because the syndrome is not consistently identified.