Drinking and Pregnancy: Is One Too Much?

[1].  In short, these studies found behavioural, delivery, physical, and cognitive problems in children whose mothers drank “moderate” amounts of alcohol or more.  For example, in an article by doctors at the University of Washington on ADD and preterm alcohol exposure, they found distractibility rates of 8%, 14%, and 46% in the low, moderate, and heavy drinking groups[2].  In another example, researchers found that children of mothers’ who drank at all during pregnancy, but especially in the last trimester, scored much worse on a cognitive test and had smaller head circumferences than women who never drank[3].  In short, it seemed that there was plenty of evidence to support the notion that women really should abstain from alcohol.

Before I get to the current research, though, let’s first think of this evolutionarily and physiologically.  Alcohol has been around for thousands of years, with anthropological findings suggesting alcohol consumption at least as early as 10,000 B.C.[4], and most cultures showing alcohol use for thousands of years.  Why is this important?  Because it suggests that there has been ample time for our bodies to adapt to certain amounts of alcohol exposure which is why for much of history, women did drink and babies turned out okay.  In fact, folklore had it that certain drinks were good for a pregnant woman (and what those drinks were depended on where you lived).  So evolutionarily-speaking, a bit of alcohol would seem to be okay.  What about physiologically?  Our bodies typically will tell us what we need and what to avoid during pregnancy by means of cravings and strong aversions (the strongest of which is morning sickness).  For many women, the fact that alcohol becomes disgusting is a sign that the fetus is in a stage whereby consumption of alcohol would harm it (typically the first trimester and last month or two when the bulk of brain development takes place).  Listening to our body is the greatest cue we have as to what our baby needs and doesn’t want during pregnancy.  Personally, I hated the thought of alcohol during my first trimester and the end of my pregnancy, but thoroughly enjoyed my occasional glass of wine during months four to seven.  I would typically have around 2-3 5oz glasses of red wine per month during that time and felt absolutely zero guilt for it and in fact found it incredibly relaxing.

 
So evolutionarily and physiologically we can have the occasional drink.  However, not all women listen to their bodies during pregnancy and we also live in a society in which “occasional” is a rather underused concept.  Binge drinking is common amongst women nowadays and the idea of listening to your body is rather antiquated, leading health professionals to have to tell us what we can and cannot do.  Given this, it’s important to know what the research says and how that applies to you and as is usually the case, research changes and updates itself, meaning older work is not necessarily the most relevant or accurate.

Currently, the single largest work on pregnancy and drinking is out of the UK, specifically by Dr. Yvonne Kelly and colleagues at the Department of Epidemiology and Public Health at University College London.  Using data from the UK Millenium Cohort study, these researchers have followed child outcomes based on maternal drinking during pregnancy in terms of cognitive abilities and behavioural problems.  The last two analyses[5][6] have been for children at aged 3 and 5 and the results have been the same – there were absolutely no deficits in the children of light drinkers, defined herein as up to 1-2 drinks per week, compared to children of abstainers.  In fact, in both cases, children from parents who were light drinkers outperformed those who abstained, though the effect was very small and may be significant simply because of the large sample size.  Regardless, the results seem quite clear that small amounts of alcohol do not seem to be related to FAS, despite older research and certain mythical stories that have managed to spread and scare pregnant women everywhere.

But it is absolutely necessary to also look at some of the criticisms of this research, as there are a few points worth considering, or at least discussing[7][8].  First, the self-report nature of maternal drinking has been criticized.  In truth, self-report research has its flaws because people are rarely very accurate about their own behaviours, especially ones that can be seen in an unfavourable light.  In the current case, it would mean that many women probably underestimated how much they drank during pregnancy.  In the case of the abstainers, this would be a problem, but it seems very difficult to lie about such a thing – if you drank just once, you were put in the light drinking category, and you’d think you’d remember that, but it could mean that the abstainers had some people in their group who should have been in a different group and that may have affected the results (though they should have been found via outlier analysis and there would have had to be a lot of them given the sample size in this study).  As for the other categories, this argument actually strengthens the case that there is no link between light drinking and later problems because it presupposes women actually drank more than the 1-2 drinks per week.  So while theoretically this could be a minor concern, I would be hesitant to believe that it would have any significant effect on the findings as they have been presented.

Second, some argue that this wasn’t truly an experimental study.  For that, the authors are guilty as charged; however, no study of this kind can be experimental and none of the older studies that found a link between drinking and behaviour were experimental either, and no one is arguing that it’s a problem for them.  To be experimental, the authors would have had to find a group of pregnant women and then randomly assign them to no-drinking, light drinking, moderate drinking, and heavy drinking groups – can you imagine being put in the heavy drinking group?  Women would revolt and it would be highly unethical.  When studies aren’t experimental, one just had to take care to control for possible confounds, something the authors did in both recent papers.  Thus, I find this argument specious (practically-speaking) and dismiss it out of hand.

Third, there’s the argument that even though they haven’t found deficits yet, it doesn’t mean they won’t in the future because we’re only looking at 5 years of age.  This is true, though again, a rather spurious argument given that the authors can’t control how fast these children age, when the cohort data was collected, or have even claimed to predict what the future will hold.  Indeed, the fact that the authors continue examine the data every few years suggests they are well aware of the notion that something may change down the line.  All we can take from this is what has been presented, which is that up to age 5, there are no deleterious effects of light drinking during pregnancy and this is an important caveat for people to know in how they interpret the research for themselves.

Finally, one respondent argued that the authors also didn’t find rather severe deficits in the heavy drinking group, so how could we trust the results for the light drinking group?  I find this to be an interesting argument because on the surface, it seems quite valid, but if one thinks about it, it highlights the distinction between the current and older research.  I have already mentioned that many older studies found significant deficits in the children of heavy drinkers and even some deficits from moderate drinking, yet the current data would suggest that these deficits are not so great.  What accounts for this difference?  The difference between these earlier studies and the current work isn’t in the population, the tests, or the mothers, but rather how drinking status is being classified.  In the current work, light drinkers were mothers who consumed up to 1-2 drinks per week, moderate drinkers 3-4 drinks per week, and heavy drinkers 5 or more drinks per week.  In previous studies (e.g., [3]), light drinkers were those who consumed 0-3 drinks per day, moderate drinkers 3-4 drinks per day, and heavy drinkers 5 or more drinks per day.  In short, many of the heaviest drinkers in the current study would still fall in the light drinkers category of previous research!  There may very well be outliers in the current heavy drinkers group, and I would expect there to be given that there are some differences between the groups, but they are fewer and further between than in previous work.  In other words, the current research is really examining nuances in what would have been the previous light to moderate drinking groups and thus the previous findings simply can’t be replicated.  As an aside, I think this probably speaks to the fact that many women are reducing their alcohol intake in light of more research coming out on the dangers of alcohol both during pregnancy and in general and I firmly believe this is a good thing.

So what is the take-home message?  First and foremost, we must always remember than anything more than the occasional drink is not a good idea when pregnant.  It’s also pretty well established that the most damage is done in the first trimester, starting around week 7 or 8 when the brain starts to develop (so if you have that drink when you don’t know you’re pregnant, you’re probably okay).  This is, of course, the time when most women start to feel an aversion to alcohol – their body’s way of saying they need to back off – but for those who aren’t used to listening to their body’s cues, that’s when you want to be extra careful to keep your drinks to a minimum.  But it’s also okay to indulge in a beer, your favourite wine or a cocktail now and again.  And by now and again, the accepted definition is 1-2 drinks of standard size (which is a 5oz glass of wine, not 8) per week, not the 0-3 drinks per day previous researchers used to think of as “light” drinking (this makes me wonder how drunk everyone was on a regular basis for this to be the standard, and it also explains a lot of the adults’ behaviour I remember growing up).  The problem is when people think that their level of drinking is “light” when in reality it’s anything but.  And binge drinking?  Forget about it – that’s just toxic to a developing fetus.

For those of you who are skeptical about drinking, simply don’t do it.  Nowhere does it say that anyone should drink during pregnancy, just that having the occasional one looks like it doesn’t do any harm whatsoever.  One thing to remember is that alcohol can reduce stress.  It may not be the best way to reduce it (though red wine in moderation has heart benefits as well), but it does, and if the drink per week helps alleviate any stress for a pregnant mom, that may actually serve to protect her child (which is one of the hypotheses put forth by the UK researchers on the seemingly protective effects in the light drinking group).  As Dr. Pathik Wadhwa (a professor of behavioural science, obstetrics, and gynecology) has stated, “When the mother is stressed, several biological changes occur, including elevation of stress hormones and increased likelihood of intrauterine infection.  The fetus builds itself permanently to deal with this kind of high-stress environment, and once it’s born may be at greater risk for a whole bunch of stress-related pathologies.”[9] In other words, if having a standard size glass of wine on a Friday night helps you relax after a particularly stressful week, it’s probably better for baby than if not having it means you’re constantly on edge, so go ahead and enjoy.  And the next time you get a dirty look from someone for enjoying that glass of Merlot with dinner, feel free to speak up and make it known that the occasional glass is not harming your baby.

For more research on light drinking during pregnancy and some of the associated considerations (amount, duration, and timing of drinking) see: 

From the UK: Fetal Alcohol Syndrome

From the National Instititue on Alcohol Abuse and Alcoholism: Discussion of the various factors at play