Updated 1/28/2012: I read the journal article! There’s nothing in the original post that doesn’t line up with the actual article. I’d say some key points in the reading are:
- The relationship between alcohol and miscarriages was not included in this study, since the data was collected by a program that studied pregnancies and measured gowth and facial features of live infants.
- There were participants in the study who had more than 12 drinks per day during the 1st trimester, more than 6 per day during the 2nd trimester, and more than 4 per day during the third trimester. It’s not clear if the same women were the “leaders” during all three trimesters.
- Many women did not drink more than 1 drink per day on average or ever binge drink. Over half the women averaged 0 drinks per day during the 2nd and 3rd trimesters, as well as the 2nd half of the first trimester.
- Women who averaged at least 1 drink per day in the 1st trimester had significantly greater chance of having babies with symptoms of FAS; women who averaged under 1 drink per day still had some babies with some symptoms.
- During the second and third trimester, exposure to alcohol was linked to fewer symptoms–exposure during the 3rd trimester was only linked with decreased birth length.
- Only physical features were studied, not any cognitive or behavioral symptoms of FAS. It is thought that many milder cases of FAS include only cognitive and behavior symptoms, not physical.
My summary (I am NOT a medical professional!): Drinking during pregnancy, particularly during the first trimester is not recommended. Anything that even approaches 1 drink per day is definitely not recommended. A drink here or there during the course of a pregnancy is probably not going to cause a big problem. If you see a pregnant woman having a glass of wine at a restaurant, don’t go yell at her about it. Don’t go out and get wasted while pregnant, though.
Today I saw a rash of news articles regarding fetal alcohol syndrome (FAS) and drinking during pregnancy. I’m definitely interested in this topic, so I took a look. I was pretty surprised by what I read, so I dug a little further. I was less surprised by what I read the closer I got to the source.
Looks like a new study is being published online and will be in the April issue of Alcoholism: Clinical and Experimental Research. I read the abstract, but it costs $35 for the full text. I’m not quite that committed. I’d love to read the article, if I get to a good academic library I might give it a try. As a secondary source, it looks like a USA Today reporter interviewed the authors and read the abstract, and may have actually read the study. As far as I can tell, the rest of the news articles just read the USA today study–they usually refer to information in the USA Today interview that is not in the abstract, but don’t add any study-related information that is not in the USA Today article. This is important, because there is some key information that seems to be misinterpreted in most of those articles. Using this hierarchy of reliability, here’s my understanding of the information. My credentials: BS in biochemistry, MA in science teaching, and reading the articles as described above.
Fetal Alcohol Syndrome (FAS) is complex and involves physical and cognitive/developmental symptoms. It results from pregnant women consuming alcohol, but the quantity or timing of that alcohol consumption is not well understood. No researcher with the slightest ethics is going to do a double-blind study, and there would be serious logistical issues.
Method: This study relied on interviews of 992 pregnant women from 1978 to 2005 to record several measures of their alcohol use. A doctor examined the infants for some of the physical symptoms of FAS (note: the cognitive/developmental symptoms were not measured). The symptoms measured included the upper lip smoothness and birth length and weight. Not all symptoms were affected to the same extent.
Their results, in my words: The more a pregnant woman drinks, the more her baby will have the examined symptoms of FAS. In particular, drinking during the second half of the first trimester most affected the babies.
“These associations were linear, and there was no evidence of a threshold.” Several news articles have discussed this, but not always clearly. The threshold concept is that perhaps if a pregnant woman only drinks 1-2 drinks per week, there will be no effect, but there’s some “threshold” above which the baby will develop FAS or milder symptoms. Or, that there’s a certain “threshold” that will produce FAS and anything above that is all the same. This research found that if a woman drank twice as much, her baby was twice as affected. This supports the common recommendation that women should not drink alcohol during pregnancy–there’s no “free pass” for a certain low amount.
News article alert: The USA Today article cites several numerical results in the form of percentages of increased risk of various symptoms as the daily average of drinks increases by one. This information has been massively misinterpreted by many other articles, and not just because people don’t understand percentages. The main thing that caught my attention about the study in the first place is that several places have cited the increased risk as resulting from one drink, not an average of one more drink per day during the second half of the first trimester (days 43-84). Basically, some articles are referring to 41 drinks over the course of six weeks as “one drink.” While the research does give some solid data on the dangers of drinking during pregnancy, some articles are massively overstating the danger.
There are many studies of varying quality on this subject which frequently contradict each other. This study is not the final word on the topic, but it’s my final word for today.