Fetal alcohol exposure is usually determined through self-reported maternal consumption. Self-reported drinking, however, is often an unreliable measure. Researchers have found that the presence of certain fatty acid ethyl esters (FAEEs) in meconium may provide a dependable biomarker of fetal alcohol exposure.
Results are published in the July 2006 issue of Alcoholism: Clinical & Experimental Research
"There are only a few biomarkers that indicate if an infant has been exposed to alcohol during pregnancy, and most of them are not strictly associated with alcohol use," said Enrique M. Ostrea, Jr., professor of pediatrics at Wayne State University. "In this study, we have found a direct association between the presence of certain FAEEs and alcohol use." Ostrea, Jr. is also the corresponding author for the study.
When people drink alcohol, it combines with certain fats in the body known as fatty acids, and FAEEs are formed. These "markers" are either deposited in tissues or, in the case of a growing fetus, in fetal urine or meconium.
"People characteristically underreport the amount of alcohol they drink," said Michael Laposata, director of clinical laboratories at the Massachusetts General Hospital and professor of pathology at Harvard Medical School. "One can measure blood alcohol but it disappears from the blood relatively quickly after drinking stops, so only very recent intake can be documented. FAEEs are 'long-term markers' of alcohol intake because they stay much longer in blood than alcohol itself and, in this case, accumulate in meconium."
For this study, researchers examined 124 mother/infant pairs. Based on self reports, 93 of the mothers had consumed alcohol during pregnancy, and 31 had not. FAEEs were analyzed in the infants' meconium by a highly sensitive and specific method called positive chemical ionization gas chromatography/mass spectrometry. Results were correlated to maternal alcohol use during pregnancy.
The presence of FAEE ethyl linoleate in meconium is highly indicative of fetal exposure to alcohol during pregnancy, said Ostrea, Jr.
"The incidence of ethyl linoleate in meconium was found to be significantly higher in the alcohol-exposed group when compared to the control group," he said. "There was also a significant association between alcohol exposure and group concentrations of ethyl linoleate. Furthermore, the highest ethyl-linoleate concentration was only found in the alcohol-exposed infants."
Ostrea, Jr. said that results also suggest that FAEEs ethyl arachidonate and docosahexanoate may have potential as biomarkers of alcohol effects on the developing fetal brain.
"Polyunsaturated long chain fatty acids, such as arachidonic and docosahexanoic acids, are important for the body," he explained. "Arachidonic acid is used in the formation of important compounds called eicosanoids, while docosahexanoic acid is used for retinal and brain development in the fetus and infant. We propose that when the fetus is exposed to alcohol … arachidonic and docosahexanoic acids may become unavailable to the fetus for its developmental needs, particularly brain development. This could result in mental retardation."
"This is an important report," said Laposata. "The measurements of the FAEEs are exceedingly well done. However, the test is only able to identify about one quarter of the mothers who ingest alcohol during pregnancy." He suggested that testing expectant mothers for alcohol intake prior to delivery would have more merit than testing meconium after birth because an objective identification of alcohol intake during pregnancy could lead to intervention, possible cessation of drinking, and a better outcome for the fetus. "We have an obvious need to check mothers during pregnancy before damage to the fetus is done," he said.
Until that transpires, said Ostrea, Jr., "our manuscript is supportive of the validity of using FAEEs as biomarkers of prenatal alcohol exposure. This would allow early identification and treatment for children born with fetal alcohol effects who might otherwise not be recognized, particularly if the mother does not admit to drinking."
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