Research at the University of Wisconsin-Madison indicates that it takes high levels of alcohol to produce the facial changes associated with Fetal Alcohol Syndrome.
“Other studies document that low alcohol consumption levels during pregnancy can cause mental retardation and behavioral changes. These problems often require life-long care,” says Susan M. Smith, a nutritional scientist in the College of Agricultural and Life Sciences. “Our work indicates that it takes much more alcohol to cause deformities in the head and face. Therefore, head and facial symptoms may play too large a role in how we define who has the syndrome.
“Many children with prenatal alcohol exposure don”t meet the criteria for treatment unless they exhibit all three symptoms of FAS. If you use facial changes to screen for people with prenatal alcohol exposure, you risk missing many who deserve help,” says Smith. She studies how compounds we eat or drink affect prenatal development.
Today, FAS is the single largest cause of mental retardation in America; almost one child in a thousand is born with the syndrome. It is more common than cerebral palsy or Down”s Syndrome. The three symptoms associated with FAS are growth retardation, neural and behavioral abnormalities, and head and facial changes. The latter include a head with a small circumference, a small lower jaw, a broadened nose and thin upper lip with no dimple, or philtrum, between the nose and mouth.
Smith and research assistant Martina Cartwright studied FAS in the chick by injecting ethyl alcohol at different times and in different doses into the yolks of developing chick embryos.
They found that alcohol affects head and facial development by killing neural crest cells. In an embryo, the neural crest cells develop into facial bones and cartilage, and parts of the brain and heart.
“The damage occurs during a window 18 to 32 hours after development begins in the egg. When administered during that period, alcohol causes changes in chicks that are analogous to those of people with FAS,” says Smith. When the researchers gave alcohol before or after the critical period, it did not affect the development of the chick”s head and face.
According to Smith, it takes an alcohol level equivalent to twice the legal limit of intoxication in people to cause head and facial deformities in chicks. This level is several times greater than the alcohol level shown to cause neural and behavioral problems in rats or primates.
The period from hour 18 to hour 32 in a chick is analogous to days 15 to 22 of human fetal development, Smith says. This means that most women pass through this period before they know they are pregnant.
“The best advice for women who are trying to conceive or who are pregnant is to avoid alcohol. FAS is the only major cause of birth defects that is 100 percent preventable,” Smith says.
The research was supported by the March of Dimes Foundation, the National Institutes of Health and the UW-Madison Graduate School.