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Fetal Alcohol Syndrome

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Synonyms of Fetal Alcohol Syndrome

Disorder Subdivisions

General Discussion

Fetal alcohol syndrome (FAS) is a characteristic pattern of mental and physical birth defects that results due to maternal use of alcohol during pregnancy. The range and severity of associated abnormalities may vary greatly from case to case. However, characteristic features may include growth delays before and after birth (prenatal and postnatal growth retardation); malformations of the skull and facial (craniofacial) region; brain abnormalities; and/or additional physical findings. FAS may also be associated with varying degrees of mental retardation, learning abnormalities, and/or behavioral problems that, in some cases, may occur in the absence of obvious physical abnormalities.


Prenatal exposure to alcohol may have multiple effects, including miscarriage, growth deficiencies, intellectual impairment, or the specific pattern of malformations at the severe end of the spectrum known as fetal alcohol syndrome (FAS). More mildly affected infants and children may be said to manifest fetal alcohol effects (FAE).

The symptoms and findings associated with FAS may vary from case to case. However, characteristic features often include prenatal and/or postnatal growth retardation, resulting in low weight and height. Many affected newborns may also have increased irritability, an increased sensitivity to sounds (hyperacusis), abnormal muscle tone, and fine motor dysfunction, including tremulousness, a weak grasp, and poor hand-eye coordination.

Evidence indicates that FAS is a leading cause of mental retardation. The degree of intellectual impairment may vary from mild to severe. The term "microcephaly" indicates that the head circumference is smaller than would be expected for age and sex. Microcephaly is a common feature of FAS that is thought to be due to an overall decrease in brain growth. In addition, specific brain abnormalities have been reported in association with FAS, including absence of the band of nerve fibers that joins the cerebral hemispheres (corpus callosum) and underdevelopment of a region of the brain involved in coordinating voluntary movement (cerebellar hypoplasia).

Children with FAS commonly have deficits in learning skills, difficulties with problem solving and memory, and/or speech impairment. In addition, many have certain behavioral abnormalities, including hyperactivity, impaired judgment, easy distractibility, impulsiveness, and impaired social and adaptive behaviors. In some cases, such abnormalities may be present in the apparent absence of physical anomalies.

FAS may also be associated with certain facial features, such as short eyelid folds (palpebral fissures); vertical skin folds that may cover the eyes' inner corners (epicanthal folds); and/or a short, upturned nose with a broad nasal bridge. Additional characteristic features may include a thin upper lip; an abnormally long, smooth vertical groove (philtrum) in the center of the upper lip; a small jaw (micrognathia); and/or flattened mid-facial regions (midfacial hypoplasia). Eye abnormalities may also be present, such as unusually small eyes (microphthalmia), drooping of the upper eyelids (ptosis), and/or abnormal deviation of one eye in relation to the other (strabismus). Reports indicate that associated facial features may sometimes be relatively subtle; in addition, they may tend to become less apparent as a child reaches puberty.

In some cases, various heart defects may also be present, particularly an abnormal opening in the partition between the lower or upper chambers of the heart (ventricular or atrial septal defects). Affected infants may also have joint abnormalities, including abnormal positioning and/or decreased range of motion. Additional physical abnormalities have also been reported in some individuals with the syndrome.


Maternal alcohol use during pregnancy can result in multiple effects on the developing embryo and fetus, including fetal alcohol syndrome (FAS). The specific amount of alcohol ingestion that may cause FAS has not been determined. However, evidence suggests that moderate and high levels of alcohol consumption during pregnancy can disrupt normal fetal growth and development. Some researchers indicate that heavy drinking throughout pregnancy may lead to more severe, wide ranging abnormalities characteristic of FAS, while occasional binge drinking at high levels may result in certain FAS features, with the specific defects dependent on the time of fetal exposure.

It is not known whether the adverse effects of alcohol during fetal development may be due to the alcohol itself or one of its by-products. In addition, the potential contributing role of other factors remains unclear, such as genetic influences affecting alcohol metabolism or additional environmental factors (e.g., maternal tobacco use). Some investigators suggest that alcohol use may impair the transfer of certain essential nutrients via the placenta, playing some role in the prenatal growth retardation characteristic of the syndrome.

Because the amount of alcohol necessary to cause FAS is unknown, it is recommended that pregnant women abstain from drinking alcohol.

Affected Populations

Researchers estimate that fetal alcohol syndrome (FAS) occurs in approximately one to two in 1,000 live births in the United States. According to reports in the medical literature, FAS is considered the primary cause of mental retardation in the Western world.

Related Disorders

Symptoms of the following disorders may be similar to those of fetal alcohol syndrome (FAS). Comparisons may be useful for a differential diagnosis:

The use of particular medications during pregnancy (e.g., hydantoin anticonvulsants) may result in certain features similar to those associated with FAS. In addition, some chromosomal disorders and genetic syndromes may also be characterized by similar symptoms and findings in some cases. (For further information on such disorders, choose the exact disease name in question as your search term in the Rare Disease Database.)

Standard Therapies

Treatment of FAS is generally symptomatic and supportive. Early intervention is important in enabling affected children to reach their potential. Special services that may be beneficial include special education, speech therapy, physical therapy, and/or other medical, social, and/or vocational services.

Prevention of FAS is achieved by abstaining from alcohol use during pregnancy.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:

Fetal Alcohol Syndrome Resources



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Fetal alcohol syndrome

Fetal alcohol syndrome
eMedicine - Gastroschisis -Author: Ali Nawaz Khan, MBBS, LRCP, FRCS, FRCP, FRCR,

Report last updated: 2009/05/11 00:00:00 GMT+0