Alcohol Leading Known Cause of Birth Defects

April 29, 2003

Alcohol is the leading known cause of birth defects in the western world, yet, paradoxically, educational and behavioral programs to encourage pregnant women to stop drinking have met with little success.
According to researcher James West, since alcohol is a food substance and a beverage, people sometimes forget it is also an addictive drug, much less a teratogen, meaning a substance that causes birth defects. West is a Distinguished Professor and head of the Department of Human Anatomy and Medical Neurobiology at the College of Medicine of The Texas A&M University System Health Science Center. He has been researching the effects of prenatal alcohol consumption on the fetus for over 25 years, and his work has been continuously funded by the National Institutes for Health since 1979.
“Heavy alcohol consumption throughout pregnancy can produce babies with Fetal Alcohol Syndrome, or FAS,” West explained. “Signs of FAS consist of: 1) a flattened, under-developed midface; 2) pre- and postnatal growth deficiency; and 3) varying degrees of central nervous system dysfunction, resulting in a variety of deficits such as a lower IQ, learning and memory deficits, hyperactivity, fine motor control problems, and problems with ‘executive functions,’ the ability to make problem-solving decisions. In fact, our research indicates that heavy alcohol consumption during pregnancy has worse effects on the fetus than does cocaine use.
“Children with FAS often make poor decisions. They can be easily talked into doing antisocial acts. Boys with the disorder often end up in trouble with the law, and girls are more likely to become pregnant early and outside of marriage.
“FAS is unusual in that we know the cause, whereas the origins of most birth defects are not known,” he continued. “Now, if we know what causes something to happen, we can usually attack and eliminate that cause, but many women continue to drink heavily throughout their pregnancies, despite efforts to educate them about the possible negative effects on their unborn child.”
Part of the problem, West notes, is that alcoholic women either don’t know the danger of drinking during pregnancy or don’t pay much attention to warnings from their doctors. Also, it’s difficult to identify mothers at greatest risk for FAS babies, since many women tend to drink at home in secret, hiding their activities from family members and their physicians.
FAS occurs in as many as 1-3 per 1,000 live births. Unfortunately, that is only the tip of the iceberg. Another form of damage from prenatal drinking is Fetal Alcohol Spectrum Disorders (FASD), referring to deficits that occur in the absence of full FAS. FASD is thought to occur in as many as 1/100 live births in the United States.
Damage to the fetus from heavy maternal drinking was at first thought to happen early in pregnancy, but now researchers believe the greatest risk to the brain occurs during the third trimester, or last three months. Thus, if a mother who has been drinking heavily stops using alcohol at the beginning of her third trimester, damage to her baby can be reduced.
The mechanism of alcohol-damage is not well-understood at this time, since some children born to heavy drinkers don’t have the syndrome. Not all fetuses are affected in the same way, and the risk factors to determine increased vulnerability are as yet unknown. West’s research currently uses animal models and molecular biology techniques of microdissection to study individual brain cells and the genes that are being changed by alcohol consumption.
“There are still a lot of unknowns,” West said. “For example, we know that genetic differences in vulnerability to alcohol damage do exist. But we don’t understand how alcohol kills developing neurons in the fetus. If we could figure that out, we could possibly come up with an intervention strategy — for example, pharmacological therapies administered before birth — to prevent fetal damage even if we can’t get a mother to stop drinking.
“Right now, most of our efforts have to focus on how to educate children affected with FAS and that’s difficult enough, since each child is different due to the mother?s unique drinking patterns. But it would be much easier to protect the child by keeping the mother from drinking than it is to fix the child’s brain after the fact.”
Patterns of alcohol consumption may be as important as the amount a woman drinks in determining whether her baby will be harmed, West said. A lesser total amount of alcohol might be just as harmful if drunk in a ‘binge’ session, so that the mother’s blood alcohol level rises rapidly. He thinks that peak blood alcohol levels in the mother are a major factor in determining fetal brain damage.
“The minimum amount of alcohol that will cause damage to the fetus is unknown,” West stressed. “As little as one or two drinks a day may cause some damage. Therefore, for a healthier baby, women who are pregnant or considering pregnancy should stop or reduce alcohol consumption during
The Texas A&M University System Health Science Center provides the state with health education, outreach and research. Its five components located in communities throughout Texas are Baylor College of Dentistry, the College of Medicine, the Graduate School of Biomedical Sciences, the Institute of Biosciences and Technology and the School of Rural Public Health.

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