BACKGROUND
Terminology: What is Fetal Alcohol Syndrome (FAS) and what are Fetal Alcohol Spectrum Disorders (FASDs)
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Fetal Alcohol Syndrome (FAS), the most severe consequence of prenatal alcohol exposure, is defined by a characteristic pattern of facial anomalies,
growth retardation, and central nervous system dysfunction (1).
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The term Fetal Alcohol Spectrum Disorders (FASDs; 2) has been proposed to represent individuals experiencing significant impairments associated with prenatal
alcohol exposure, including not only those with FAS, but also those who might be diagnosed with other related conditions, such as Partial FAS, Alcohol Related
Neurodevelopmental Disorder (ARND), or Alcohol Related Birth Defects (ARBD).
Significance: Why is it important to assess for prenatal alcohol exposure and FASDs?
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Prenatal alcohol exposure is considered to be the most common known cause of mental retardation,
which suggests that the most common known cause of mental retardation is potentially 100% preventable.
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The most recent estimates by NIAAA indicate that FAS costs the U.S. over 4 billion dollars per year (3).
Although the costs for the entire spectrum of FASDs are unknown, they are expected to be considerably higher (4).
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Despite the fact that FAS was identified in this country more than 30 years ago (1),
and despite intensive public awareness campaigns, prenatal alcohol exposure continues to be a significant public health concern.
- Public awareness messages (i.e., alcohol warning labels) do not appear to be very effective for women who are moderate or heavy drinkers (5).
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Even when women are relatively knowledgeable about the risks of prenatal alcohol use, this knowledge does not necessarily translate into healthy behavior during pregnancy.
A recent study found that women's pre-pregnancy drinking was a much stronger predictor of their prenatal drinking than was their knowledge regarding the risks of prenatal alcohol use
(6).
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Approximately 1 in 8 pregnant women (or 500,000 pregnant women) consumes one or more drinks per week.
80,000 of those women are drinking at levels that are associated with significant negative effects on fetal development.
Furthermore, more than half of non-pregnant women report drinking alcohol, and 1 in 8 report binge drinking in the prior month.
Given that almost half of the pregnancies in this country are unplanned, and that many women are unaware they are pregnant until
the sixth week of pregnancy, prenatal alcohol exposure continues to represent a major public health concern (7).
Incidence: How common are FASDs?
- Most recent studies (8) suggests that the overall incidence of FAS in the United States is between .5 and 2 per 1,000 births
- If we consider the full spectrum (e.g., Partial FAS, Alcohol Related Neurodevelopmental Disorder), the incidence rises to at least 1 in 100 (10 in 1,000)
- This estimate translates into approximately 40,000 children every year born with FAS or another alcohol related disorder.
- In some high risk populations the rates can be considerably higher:
- Recent study of consecutive admissions to a child psychiatric inpatient unit found 30% of the patients had documented prenatal alcohol exposure and, within the exposed group, 26% met full criteria for FAS (9).
- Children with FASDs are also over-represented in foster care, with rates being 10-15 times higher than in the general population (10).
- In families in which one child is diagnosed with FAS, the incidence of FAS among older siblings is 170 in 1,000, and among younger siblings, it is 771 in 1,000
(11), highlighting the importance of patient education and prevention.
- Notably, FASDs are more common than other more well-known developmental disabilities, such as Down syndrome or autism.
Course: What is the prognosis for individuals with FASDs?
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Long-term studies that have followed individuals with FAS into adolescence and/or adulthood have found persistent cognitive, behavioral,
and physical problems (12,13).
- For example, the work of Ann Streissguth and her colleagues have found among individuals with FASDs who were followed into adulthood:
- 94% had mental health problems,
- 61% had experienced disruptions in their education (expulsion, dropping out, etc.)
- 60% had experienced trouble with the law
- 35% had alcohol and/or drug problems.
- Factors that have been found to increase the risk for negative outcomes among individuals with FASDs include: (13)
- Lack of a diagnosis before age 12
- Living in an unstable, non-nurturing environment
- Being diagnosed with Fetal Alcohol Effects rather than Fetal Alcohol Syndrome
- Having an IQ > 70
- It is notable that individuals who do not meet the full criteria for FAS, but instead are diagnosed with Fetal Alcohol Effects (ARND) and those with IQ's above 70 are at greater risk for adverse outcomes, including disrupted school experiences and alcohol/drug problems (for both groups) and for trouble with the law (for individuals diagnosed with FAE).
- It seems likely that these individuals may be at increased risk because they may be less readily identified as needing services, and are less likely to qualify for and receive services than either individuals who meet full criteria for FAS or those with IQs below 70.
Moderating factors:
Level of exposure
- A number of factors may moderate the impact of prenatal alcohol exposure on a developing fetus.
- A question that is frequently asked is, "How much alcohol is it safe to drink during pregnancy?"
- In general, there appears to be a dose-response relationship between maternal drinking and fetal outcomes.
That is, children who were exposed to higher levels of alcohol in general show more effects than children who
were exposed to lower levels of alcohol (14).
- However, it is important to remember that at this time, there is no established safe level of maternal
alcohol consumption during pregnancy.
- Cognitive and growth effects have been found with ½ drink three times per week (
15, 16).
- Recent animal studies (17) suggest that just two drinks consumed
during pregnancy may be enough to kill some developing brain cells, leading to permanent neurological
damage, suggesting that there is no known safe level of alcohol consumption during
pregnancy.
- Moreover, the peak blood alcohol concentration (BAC) to which the embryo or fetus is exposed is a
key factor that affects fetal brain development. That is, higher BAC levels are associated with more
severe fetal brain injury (18).
- Women vary in their ability to metabolize alcohol for a number of reasons (e.g., age, genetics),
and thus two women may drink the same amount of alcohol and have very different BAC levels. Thus, it
is impossible to predict with any certainty what level of alcohol might lead to a very low BAC for one
woman and what level might lead to a very high BAC for another woman.
- Consequently, the safest approach is for women who are pregnant, trying to get pregnant, or who are sexually active but not using contraception to completely abstain from alcohol.
Pattern of exposure
- Although there is no established safe level of maternal alcohol consumption during pregnancy, a woman's pattern of drinking may have an impact on the likelihood and severity of fetal brain damage.
- Binge drinking appears to be particularly harmful to the developing fetus, probably because it's associated with higher blood alcohol concentrations
- Animal studies demonstrate that:
- If the same total dose of alcohol is administered in two patterns: continuous exposure (24 hours per day) or condensed exposure (12 hours per day), the group with condensed exposure has higher BAC levels and lower brain weights than the group with continuous exposure (19).
- A lower dose of alcohol can result in higher BAC levels and greater damage to the developing brain than a higher dose of alcohol, if the lower dose is administered in a more condensed pattern (e.g., over a 4 or 6 hour period, and the higher dose is administered in a more continuous pattern (e.g., over a 24 period) (20).
- Human studies
- Binge drinking has been found to be a stronger predictor of neurobehavioral deficits, including problems with attention, memory and cognitive processing than other more commonly used measure of prenatal alcohol consumption, including average amount per day and frequency of drinking (21).
- However, keep in mind, as was discussed earlier, even lower levels of drinking can harm fetal development, so again, the safest approach is to completely abstain from alcohol during pregnancy.
Timing of Exposure
Another question that is frequently asked: "Is there any time during pregnancy when is it safe to consume alcohol?"
- Timing of Exposure
- Alcohol has different effects on the developing fetus depending on when the exposure occurs (22)
- 1st trimester
- Major morphological/structural abnormalities
- Facial features
- Because organogenesis occurs 2-8 weeks, exposure during this time may result in cardiac or renal malformations
- 2nd trimester
- Increased risk of spontaneous abortion
- 3rd trimester
- Growth retardation
- Particularly vulnerable period for brain development
- However, because the central nervous system development occurs throughout pregnancy, again there is no safe period during pregnancy for alcohol consumption
Figure reprinted with permission from: Streissguth and Little (1994, 23)
So what is the best way to prevent FASDs?
- In February, 2005, the Surgeon General issued the following updated advisory:
- A pregnant woman should not drink alcohol during pregnancy.
- A pregnant woman who has already consumed alcohol during her pregnancy should stop in order to minimize further risk.
- A woman who is considering becoming pregnant should abstain from alcohol.
- The Surgeon General concludes from the current research that:
- No amount of alcohol consumption can be considered safe during pregnancy.
- Alcohol can damage a fetus at any stage of pregnancy. Damage can occur in the earliest weeks of pregnancy, even before a woman knows that she is pregnant.
- To read the entire advisory from the Surgeon General, go to: http://www.surgeongeneral.gov/pressreleases/sg02222005.html
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