Fetal Alcohol Syndrome

September 11, 2011

Fetal alcohol syndrome (FAS) is a pattern of birth defects resulting from drinking alcohol during pregnancy. Fetal alcohol syndrome occurs in 1 out of every 750 births. It was formally recognized and named in the early 1970s and is currently the leading cause of mental retardation in the United States. Alcohol is directly responsible for up to 20% of cases of mental retardation with IQs in the 50-80 range (100 is considered normal); the average IQ for a child with fullblown Fetal alcohol syndrome is 63. Fetal alcohol syndrome is completely preventable if a woman does not drink alcohol during her entire pregnancy. Exactly how alcohol causes Fetal alcohol syndrome is not well understood on a molecular level.

Symptoms of Fetal alcohol syndrome are irreversible, and the brain damage caused by alcohol in a developing fetus is permanent. Children with Fetal alcohol syndrome never “catch up” physically or mentally. Therefore, the best treatment for this condition is prevention. All women of childbearing age need to be screened for alcohol use disorders. Surveys estimate that 3.5% of pregnant women have a “frequent drinking” pattern, defined as two or more drinks per day or more than five drinks per occasion; 16.3% of pregnant women reported “any drinking,” defined as at least one drink in the preceding month. Appropriate counseling techniques and referrals for ongoing treatment will help reduce or eliminate drinking before conception and during pregnancy.

Several factors help determine the effect alcohol will have on the fetus. Timing and dosage of alcohol exposure are important. Alcohol is most damaging in the first trimester of pregnancy. When the mother drinks, the fetus has the same blood alcohol level as the pregnant woman. However, because of its small size and immature liver, the fetus can stay drunk for 3-4 days even though the mother is only drunk for several
hours. Binge drinking (defined as two or more drinks per hour) has been found to be more detrimental to the fetus than low-level, chronic drinking. However, because there is no proof that small amounts of alcohol are safe, the best advice is for women to completely abstain from alcohol during pregnancy.

Other factors that determine the effects of alcohol on the developing fetus include nutritional factors, metabolic factors, individual factors of the mother and child, and genetic factors. Among women who drink, risk factors for Fetal alcohol syndrome include increased marital age, higher number of previous children, low socioeconomic status, other drug use, or a previous child with Fetal alcohol syndrome.

Genetic factors can influence the incidence of Fetal alcohol syndrome. One study reported that Southwest Plains Indians had an Fetal alcohol syndrome rate of 9.8 per 1,000 live births, compared to a worldwide incidence of 1.9 per 1,000 live births. Southwest Plains Indians lack or have a reduced amount of an enzyme necessary to break down alcohol, causing higher and longer levels of alcohol exposure to the fetus.

The diagnosis of Fetal alcohol syndrome is based on four criteria: prenatal alcohol exposure, growth retardation, facial malformations, and neurodevelopmental problems. The criteria for growth retardation include weight and height that fall below the 10th percentile. More than one, but not necessarily all, of the following facial malformations must be present: short palpebral fissures, thin upper lip, indistinct philtrum, short nose, and flat midface. Other associated facial features may be present, but are not sufficient to determine the presence of Fetal alcohol syndrome; these include epicanthal folds, a low nasal bridge, abnormal smallness of the jaw, and minor ear anomalies (Figure 1).

Figure 1. Facial features particularly characteristic of a child with fetal alcohol syndrome (FAS). Discriminating features (i.e., those considered definitive signs of FAS) are shown on the left side of the illustration; characteristics listed on the right side are associated with FAS but are not sufficient to determine the presence of the syndrome. Microencephaly (small head circumference) is not a facial feature per se, but a central nervous system characteristic. (Palpebral fissures = eye opening; philtrum = groove between nose and upper lip; epicanthal folds = skin folds covering inner corner of the eye; micrognathia = abnormal smallness of the jaw.) (Source: Streissguth & Little, 1994.)

A wide variety of neurodevelopmental disorders are associated with Fetal alcohol syndrome, including microcephaly (head circumference less than the 10th percentile), memory problems, impaired emotional attachment to caregivers, impaired motor skills, neurosensory hearing loss, learning disabilities, impaired visual/spatial skills, intellectual impairment, problems with reasoning and judgment, attention deficit disorder, and hyperactivity. More than one of these neurodevelopmental disorders may be identified, but not all conditions need to be present to diagnose Fetal alcohol syndrome.

Children who do not meet all four criteria for Fetal alcohol syndrome may still be injured by maternal alcohol use, in a condition that used to be known as fetal alcohol effects (FAE). In medical practice, FAE has been replaced by two terms, alcohol-related birth defects (ARBD) and alcohol-related neurodevelopmental disorder (ARND). ARBD includes abnormalities of the face, eyes, ears,
heart, brain, kidneys, and limbs. Some examples of ARBD are atrial septal defect, ventral septal defect, bulging eyes (ptosis), low-set posterior rotation of the ear, poorly developed or absent kidneys, fusion of the radius and ulna bones in the forearm, and abnormal palmar creases. ARND includes changes in behavior, cognitive function, language, attention, memory, attachment, and fine motor skills.

SEE ALSO: Addiction, Alcohol use, Pregnancy, Substance abuse

Suggested Reading

  • Centers for Disease Control and Prevention. (1997). Alcohol consumption among pregnant and childbearing-aged women— United States, 1991 and 1995. Morbidity and Mortality Weekly Report, 46(16), 346-350.
  • Identification and care of fetal alcohol-exposed children: A guide for primary-care providers. (1999). NIH Publication No. 99-4369. Rockville, MD: NIAAA.
  • Identification of at-risk drinking and intervention with women of childbearing age: A guide for primary-care providers. (1999). NIH Publication No. 99-4368. Rockville, MD: NIAAA.
  • Stratton, K., Howe, C., & Battaglia, F. (Eds.). (1996). Fetal alcohol syndrome: Diagnosis, epidemiology, prevention, and treatment. Washington, DC: National Academy Press.

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