Elizabeth Austin
IF you're pregnant, don't drink. That's been conventional wisdom since the early 1970s, when researchers first identified a pattern of mental retardation and other birth defects called foetal alcohol syndrome (FAS). Heavy drinking during pregnancy, says Averette Mhoon Parker, M.D., an expert on substance abuse at the Center for Substance Abuse Prevention in Washington, D.C., is "the only completely preventable cause of retardation."
No one knows precisely how much alcohol it takes to damage the growing foetus, says Alice Kirkman, a spokeswoman for the American College of Obstetricians and Gynaecologists, "but your safest plan is not to drink at all during pregnancy."
Admittedly, no study has proven that a single celebratory glass of champagne harms a foetus. "We don't really know why some women can drink heavily during their entire pregnancies and yet have healthy, normal babies," says Parker. In fact, until the '70s, obstetricians routinely reassured their patients that the placenta protected the foetus from its mother's indulgence. Now it's known that substances consumed by the mother can have devastating results.
A heavy drinker - averaging three or more drinks daily - can cause her offspring to exhibit the classic facial features of FAS: short eye openings; a thin upper lip with no middle groove; an elongated, flattened midface and a short nose with a low bridge. Just by looking at an affected new-born, an expert can suspect it has FAS. Mental retardation, hyperactivity and attention-span disorders may show up as the child develops.
Other alcohol-related birth defects can include congenital heart disease, hearing loss, vision problems and abnormalities of the urinary tract and genitals. Spina bifida, a defect of the spinal column that can cause severe physical and mental handicaps, is up to 60 times more common in babies exposed to alcohol before birth, according to the National Institute on Alcohol Abuse and Alcoholism. A report from the U.S Department of Health and Human Services claims that the risks of alcohol-related defects rise with the mother's age and number of children.
Researchers aren't sure precisely how alcohol causes harm. Studies of the placenta reveal that alcohol inhibits the transport of amino acids and glucose. Alcoholic mothers or their infants can also be deficient in trace metals and vitamins. And foetal damage may be caused by hormonal deficiencies, diminished oxygen delivery and impaired function of proteins known as "growth factors" that help develop both nerve and muscle cells.
Experts do know that the foetus is especially vulnerable early in pregnancy, when the major body systems are being developed. And since the brain is among the first organs to develop and the last to be completed, it is highly susceptible to damage throughout pregnancy.
Most studies on FAS link foetal damage to average daily intake, but Maria Testa, Ph.D, a research scientist at the Research Institute on Addictions in Buffalo, New York, notes that few Americans follow the common European pattern of drinking a small amount of alcohol every day. Drinkers in the U.S, she says, tend to consume more alcohol at one sitting.
No one knows for sure, but studies on animals suggest that the mother's occasional-but-high peak blood alcohol levels can affect the foetus in a way that constant low levels don't. "Binges are likely to be more dangerous than one drink a day," says Testa.
Because of their different metabolic rates, a foetus may be harmed by an alcohol level that has little apparent effect on the mother. "A drink that will take a mother a couple of hours to metabolise can take the foetus three times as long because of the immaturity of its organs," says Parker.
Alcohol may affect individual foetuses differently, just as it does adult. "Because of constitutional factors, we can't come up with an equation that assumes it's safe to have three drinks but not four," says Parker.
Why pregnant
women drink
The government's massive public health campaign alerting pregnant women to the dangers of alcohol has increased awareness enormously, says Testa. Most women take those warnings to heart. Unfortunately, the women most likely to continue drinking are those who drink the most. "It's difficult for an addicted person to give up drinking even when pregnant" she says. "Seeing a sign on the bus warning about alcohol isn't going to stop a heavy drinker."
Testa research found that women who drank heavily during pregnancy viewed alcohol as somewhat less risky than did abstainers. She also found that a big problem of heavy drinkers was trying to abstain when spouses and friends were drinking.
Better late than never
Although some women continue to drink during pregnancy, Parker stresses it's never too late to stop. "Some people feel that drinking is like dieting, that once you're off your diet, you might as well not go back on. Women may believe that since they've been drinking this far along, it doesn't matter whether they stop or not," she says. But women who give up alcohol after drinking heavily through part of their pregnancies generally have healthier babies than those who continue for nine months. "Whenever an expectant mother stops drinking, the foetal outcome is better," says Parker, "even if she stops at the beginning of the last trimester."
Women who spend their pregnancies worrying about the possible effects of the glass of wine they drank the day after conception should relax. "While we can't say that one drink a week is 'safe', we can say that it doesn't appear to be associated with harmful effects," says Testa. "Nevertheless, many experts advise abstention as the only way of eliminating any risk."
"Lots of women can't tolerate alcohol consumption or cigarette smok e while they're pregnant" adds Parker. "I guess that's simply Nature's way of saying "Don't do that."
