Fetal alcohol syndrome, fetal alcohol effects

Philippe Jeanty, MD, PhD Sandra R Silva, MD

Updated 2006-01-18 by Juliana Leite, MD

Original text 1999-05-18 Philippe Jeanty, MD, PhD & Sandra R Silva, MD

Synonyms: None.

Definition: Alcohol use during pregnancy results in a spectrum of adverse outcomes known as fetal alcohol spectrum disorders. Fetal alcohol syndrome (FAS) is one of these disorders. Fetal alcohol syndrome is characterized by specific facial abnormalities and significant impairments in neurodevelopment and physical growth. Children exposed to alcohol (approximately 45-50 g of ethanol per day or equivalent) in utero suffer from growth and mental retardation, physical abnormalities, and immune dysfunction. There is no "threshold†so some fetuses exhibit signs of fetal alcohol effects at lower exposure. Recommendations for clinicians regarding assessment of thresholds published by the National Institute on Alcohol Abuse and Alcoholism recommend that any woman who reports drinking more than 7 drinks per week or more than 3 drinks on any given day be further assessed for risk of developing alcohol-related problems.

Incidence: The incidence of FAS ranges from 2—30:10,000 live births. This represents the most common form of mental retardation in the United States. In the United States, the prevalence of FAS has been estimated to fall between 0.5 and 2.0 cases per 1000 births. It has been long recognized that the true extent of teratogenic injury from alcohol exposure exceeds the clinically recognized prevalence of FAS, as behavioral and physical teratogenesis may be present in the absence of full expression of the syndrome.

Etiology: Direct toxicity of alcohol and its metabolites that cross the placenta and are not detoxified by the fetal liver.

Diagnosis: The findings include microcephaly, long round philtrum, small micrognathia, cleft palate, suppression of the Cupid arch, microphthalmia, microcephaly, dysgenesis of the corpus callosum, malformed ears, atrial septal defect, ventricular septal defect, and growth restriction predominantly involving the limbs and occurring early without oligoamnios. This lack of specificity suggests that the FAS facies may be a common teratogenic expression of exposure to a variety of substances occurring during a defined period of fetal development.

Differential diagnosis: Other conditions that involve growth restriction and microcephaly such as toxoplasmosis, rubella, cytomegalovirus, herpes simplex (TORCH) and chromosomal anomalies.

Prognosis: Mental retardation and delay in growth that persists postnatally. Most children with FAS are mildly to moderately retarded, but intellectual ability varies widely. The severity of mental retardation appears related to the severity of growth deficits and dysmorphogenesis, such that the more phenotypically affected individuals have lower IQ scores. Hyperactivity is frequently observed. As adults, mental illness is highly prevalent with FAS, affecting over 70% in one series in which 60% had alcohol or drug dependence, 44% depression, and 40% psychosis.

Management: The management of these pregnancies should be aimed at reducing the alcohol consumption; few programs have had much efficacy.

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