Alcohol-Related Birth Defects

Critical Periods for Prenatal Alcohol Exposure

Studies have shown that the number of women who drink during pregnancy far outnumber the number of children born with an ARBD, indicating that not all children are affected by in utero alcohol exposure. Additionally, children who are affected by maternal alcohol use do not show uniform deficits. There are, however, some factors that have been shown to increase the likelihood of an ARBD occurring, such as [Page 54]the mother's particular metabolism, the pattern of drinking that occurred during pregnancy, and genetic differences. As for the particular type of ARBD that occurs, the most important factor is believed to be the timing of the alcohol exposure during pregnancy, or critical period. For example, early exposure to alcohol causes more craniofacial damage in comparison to exposure later on in the development of the fetus. One particularly significant critical period for fetal development is during the first two months of gestation, which is called the embryonic period. During this time the fetus is undergoing organogenesis, a period in which the majority of organs are forming. Exposure to alcohol during organogenesis can cause severe physical defects characteristic of children born with FAS. Alcohol exposure can also affect the development of sex organs if exposure occurs around the 10th week of gestation, the time in which sex organ differentiation occurs.

Binge Drinking in Pregnant Mothers

A major area of concern for the development of an ARBD is binge drinking among pregnant mothers. Binge drinking is defined as consuming four or more drinks on one occasion for women and five or more drinks on one occasion for men. Although research on this topic is controversial, it has shown that binge drinking tends to be more harmful than other patterns of drinking because it causes significant damage to the brain of the developing fetus. In comparison to more common patterns of drinking, binge drinking episodes cause more prolonged exposure of alcohol to the fetus. This damage can cause global impairment in behavior. For example, binge drinking during pregnancy has been linked to more disinhibited behaviors in the children, when compared to those children who had mothers who did not binge drink. Further, there is strong evidence to suggest that binge drinking may result in lower verbal IQs, more delinquent behaviors, and a greater chance of developing psychological disorders.

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