Is consuming alcohol during pregnancy still taboo? Based on numerous studies published over the last 8 years, trends have emerged that some expecting mothers and health professionals appear to be open to drinking alcohol during pregnancy. I have seen this on the news, mom focused blogs, social media, and through personal experience with friends and coworkers. This past summer, I met a woman who was drinking several mimosas at a wedding, while explaining to everyone that her doctor told her 1-2 glasses of wine per day are perfectly fine. She was in her 3rd trimester. Have the historical recommendations to strictly avoid alcohol changed and are there no adverse outcomes to infant health with small to moderate amounts of alcohol? The lack of consensus on this controversial topic has created debate on what the best recommendations are and what should be included in national policies1.
What can happen?
Fetal alcohol spectrum disorders (FASDs) are a group of conditions caused by the consumption of alcohol during pregnancy, as the alcohol is passed to the baby through the mother’s umbilical cord2. The effects of FASDs can include physical, behavioral and intellectual disabilities. Drinking alcohol during pregnancy can also cause stillbirth or miscarriages. Characteristics of babies affected by FASDs include facial abnormalities, small head size, shorter than average height, low body weight, poor coordination, hyperactivity, difficulty with attention, poor memory, learning disabilities, speech and language delays, low IQ, poor reasoning and judgement, vision and hearing impairments, and problems with the heart, kidneys or bones2. There are several types of disorders on the fetal alcohol spectrum, which include Fetal Alcohol Syndrome (FAS), Alcohol-Related Neurodevelopmental Disorder (ARND), Alcohol-Related Birth Defects (ARBD), and Neurobehavioral Disorder Associated with Prenatal Alcohol Exposure (ND-PAE) 2. The CDC recommends that women of childbearing age do not drink alcohol unless contraceptives are used, as nearly 50% of pregnancies in the US are not planned2. Women may not know that they are pregnant for up to 6 weeks, which can increase the chance of the baby being exposed to alcohol. Although the exact prevalence of FASDs are unknown, it is estimated that 2-5% of the population is diagnosed on the spectrum3. Based on national surveillance data from 2011-2013, one in ten women report alcohol use during pregnancy and one in thirty-three report binge drinking, defined as four or more drinks on one occasion3. It is recognized that self-reported alcohol use is generally underreported. An objective from Healthy People 2020 is to increase the abstinence of alcohol in pregnant women in order to reduce the amount of alcohol related adverse birth outcomes.
The controversy has surfaced that based on more recent studies, the perception that small amounts of alcohol do not pose a concern during pregnancy. The Danish National Birth Cohort registry is the first large scale epidemiological study, including 100,418 pregnant women, in which the aim is to follow women and children from the first trimester of pregnancy throughout life4. The results have shown that women who drank less than 3 drinks per week did not have an increased risk of preterm delivery in the first trimester. A standard drink is defined as 12 g of alcohol in Denmark. Historically, studies have grouped low and moderate drinking together in comparison to heavy drinking. One study separated low and moderate amounts of alcohol exposure and examined prenatal drinking with neonatal outcomes5. They found no association with light alcohol use and low birthweight, length of gestation and asphyxia. Moderate drinking and binge drinking were not related to length of gestation when adjusted for in the analysis, however they were both related to a higher risk of asphyxia at birth and lower birth weight. This is most likely due to the effect of alcohol exposure constraining fetal growth. The study included 1,258 pregnant women and self-reported questionnaires were used. Low levels of alcohol were considered less than 2 glasses per week, moderate levels were 2-4 glasses per week and high levels were 5 or more glasses per week. Binge drinking was defined as 3 or more glasses on one occasion. Covariates including smoking, child gender, maternal age, occupational status, income, citizenship, the use of prescription or illicit drugs, and all covariates were adjusted for in the analysis. They found that alcohol consumption during pregnancy was higher in women who were 30 years or older, had a higher occupational level and in those who reported illegal drug use. It was noted that a considerable number of participants did not select an answer regarding binge drinking on the questionnaire. The authors also recognized that other confounders such as lifestyle factors may have been missed, such as high blood pressure and that future studies need to focus on the timing of alcohol exposure during gestation. They explained that the limited sample size affects statistical power and could increase the chance of error in the results.
Digging into the research.
Another population based study with a sample size including 4,714 women and infants focused on timing of alcohol exposure during pregnancy6. They found that the first trimester was the most dangerous time to drink heavy amounts of alcohol. However, they did not find an association between birth defects related to low to moderate intake of alcohol throughout pregnancy. A standard drink was considered 10 g of alcohol. Low to moderate amounts of alcohol were defined as <70 g of alcohol per week and heavy amounts were defined as >70 g of alcohol per week. The type of alcohol was not specified. They still acknowledge that the safest choice is to avoid alcohol specifically to prevent the possibility of behavior issues in children. The authors recognize that recall bias is a limitation and state that this study needs to be repeated with a larger population to confirm the results.
A study that analyzed data from a large prospective cohort with a homogenous population, found no significant association with neurodevelopment of children at 5 years of age, from moms who reported low to moderate amounts of weekly intake of alcohol, including binge drinking, during early to mid-pregnancy7. Measures of neurodevelopment included intelligence, attention and executive function. Low to moderate amounts of alcohol were defined as 1-8 drinks/week and binge drinking was defined as five or more drinks on a single occasion. Beer, wine and spirits were all included in the data and one standard drink was considered 12 g of alcohol. Child outcome at 5 years of age and maternal IQ were both assessed by trained psychologists. Mothers also completed the Behavior Rating Inventory of Executive Function (BRIEF) Parent Form. There were 1,337 cases with complete information included in the study. Confounding factors and potential interactions included parental education, IQ, smoking, gender, age, marital status, pre-pregnancy BMI, prenatal average number of drinks per week, prescription medications, home environment, health status and hearing and vision abilities and were accounted for in the multivariate analysis. Information bias must also be considered in such a study; however, the authors note that the method used to analyze the data added to the statistical power and diminished bias. Other limitations include the fact that a null effect could potentially mean that the study design could have “failed to detect a true effect”. In conclusion, it was recognized that although there is no safe level for alcohol consumption during pregnancy and although advice to abstain from alcohol continues to remain current, it does not appear to impact neurodevelopment when small to moderate amounts of alcohol are consumed throughout early to mid-pregnancy.
A survey published in 2010, asked OB-GYNs about their practice patterns regarding alcohol consumption during pregnancy8. Interestingly, among these practitioners, they found no consensus on whether the effect of alcohol is clear on fetal development. Most of the doctors asked their patients about alcohol intake in the initial appointment but only a low number asked during follow up visits. Many responded that they were not aware there are professional tools including a clinician’s guide and prevention tool kit available regarding Fetal Alcohol Spectrum Disorder and alcohol use. A focus group found that some participant’s midwives were recommending wine for stress relief during pregnancy and that it is even beneficial for the developing baby9. Perhaps, this thought stems from research on the benefits of wine and heart health. However, it is noted in the same article that, “no research to date has found that alcohol consumption improves the physical health of a developing baby, and it is recommended that pregnant women abstain from all types of alcoholic beverages.”
People may also argue that alcohol is part of their culture, especially in certain countries and that it should be a personal decision based on a discussion with their doctor. Recommendations vary across the world. The International Alliance for Responsible Drinking compiled a detailed table for guidelines in 54 different countries on alcohol consumption for women who may become pregnant, are pregnant and also for women who are breastfeeding10. Overall, this chart shows that the general consensus appears to be that abstaining from alcohol during pregnancy is the best policy among these countries, with few exceptions. These conservative recommendations even exist in Denmark, where much of the data on this topic has emerged from the Danish National Birth Cohort. This chart was last updated in February 2016. The standard drink varies among these countries from 8 to 20 grams and no standard amount is defined in 16 countries on the list. This is important information because when research methodologies include a standard drink unit, the results can vary among a specific population depending on the amount of alcohol exposure. Notably, the national guidelines in England recommend that alcohol should be avoided by women planning to conceive and also for women who are in the first trimester11. After the first 3 months, if a woman chooses to drink alcohol, it should be limited to no more than 1-2 units per week. One unit is defined as a small glass of wine or half a pint of beer or cider. They caution that the quality of data is poor and that although there is no evidence of harm in these guidelines, they are not able to guarantee there will be no harm with fetal outcomes.
A systematic review focusing on low to moderate amounts of alcohol exposure on pregnancy outcome, found that although there is no convincing evidence of adverse effects at these levels, the evidence is not strong enough to justify a safe level during pregnancy13. The authors state that the existing evidence is inconclusive. Limitations of the systematic review include publication bias, where studies with positive results may have been more likely to be published and therefore included in the review. It is also noted that when women are asked after delivery to recall how much alcohol was consumed during pregnancy, the potential for recall bias is apparent because the outcome is already known, as the baby has been born at that point. The generalizability across countries is also questionable.
Factors to consider.
Limitations of the available studies must be considered. Factors such as smoking, drugs and socioeconomic status can influence fetal outcomes and study results. Due to fear of social acceptability, mothers could potentially underreport their alcohol consumption, affecting the comparison groups being investigated and even mask harmful effects13. Two other limitations of many available studies are that participants are only asked about when they were drinking at one point during pregnancy and also what their overall average intake was, which does not give a detailed picture of the pattern in regards to frequency, quantity, variability and timing7. This could be significant if the timing of when the alcohol is consumed matters, such as during a specific trimester. The definition of how much “one drink” is could also vary and people are not always clear on how much alcohol is their drink1. There is no exact definition of light, moderate or heavy drinking. Also, whether the study accounts for binge drinking, such as 5 in one night compared to 1 drink over 5 days, could potentially impact the outcome. Misclassification is another methodological error that can occur in studies regarding fetal outcomes with pregnancy13. Other than specific facial abnormalities, it can be difficult to determine the cause of birth defects because they can be caused by factors other than alcohol exposure6. In fact, Institute of Medicine guidelines recommend that all other diagnoses are first excluded before a birth defect is attributed to prenatal alcohol consumption6. More population based studies are needed to strengthen the evidence6. Limitations of a focus group include a potential for bias and participants are not considered generalizable to the population9. Due to child development, the effects of alcohol could potentially be detected as the children become older and studies of older children should be investigated to address this7. Experimental studies investigating the effect of alcohol on pregnancy would not be ethical in this population. On a similar note, one paper that looked at evidence from systematic reviews and meta-analyses, explained that it would be unethical for policies and guidelines to state that it is ok to drink alcohol, due to the risk of harming the fetus1. It is possible that studies may have failed to adjust for confounding factors such as smoking and socioeconomic status, ultimately distorting results14. In addition, results can be affected due to poor memory recall and information influenced by culture. If these studies are showing that mothers who are educated and affluent are more likely to drink low to moderate amounts of alcohol, it must be considered that those children could be more successful due to their environment when it comes to tests that measure intelligence and outcomes. In reality, the risk of alcohol causing harm to the fetus can vary depending on an individual basis among women. A woman’s genetics or other factors independent to alcohol consumption could potentially predispose children to behavior problems or adverse outcomes15. In fact, a paper published in the International Journal of Obstetrics and Gynecology stated, “It is important to note that the conclusions drawn are based on the sample population under study, not on individuals15.”
The bottom line.
When looking at epidemiologic studies, it must be acknowledged that even though there may be limited evidence that low amounts of alcohol during pregnancy does not pose a threat at the present time, this doesn’t necessarily mean that there won’t be harm to the fetus when alcohol is consumed. Conservative recommendations to abstain from alcohol are generally well known, as there is no safe level established during pregnancy. According to the CDC, all types of alcohol are equally harmful. The CDC also conveys the message that, “When a pregnant mom drinks alcohol, so does her baby,” and that FASDs are 100% preventable if women abstain from alcohol during pregnancy16.
- O’Leary CM, Bower C. Guidelines for pregnancy: What’s an acceptable risk, and how is the evidence (finally) shaping up? Drug Alcohol Review. 2012; 31: 170–183. doi: 10.1111/j.1465-3362.2011.00331
- Morbidity and Mortality Weekly Report (MMWR). Alcohol Use and Binge Drinking Among Women of Childbearing Age – United States, 2011-2013 Weekly. Centers for Disease Control and Prevention website https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6437a3.htm?s_cid=mm6437a3_e Published September 25th, 2015. Page last reviewed and updated September 25th, 2015.
- Andersen AMN, Olsen J. The Danish Fetal Alcohol Spectrum Disorders. Centers for Disease Control and Prevention website. https://www.cdc.gov/ncbddd/fasd/facts.html Page last reviewed and updated June 6th, 2017.
- National Birth Cohort: Selected scientific contributions within perinatal epidemiology and future perspectives. Scandinavian Journal of Public Health, 2011; 39(Suppl 7): 115–120 doi: 10.1177/1403494811407674
- Meyer-Leu Y, Lemola S, Daeppen JB, Deriaz O, Gerber S. Association of Moderate Alcohol Use and Binge Drinking During Pregnancy with Neonatal Health. Research Society on Alcoholism. 2011; 35 (9): 1669-1677. doi: 10.1111/j.1530-0277.2011.01513
- O’Leary CM, Nassar N, Kurinczuk JJ, de Klerk N, Geelhoed E, Elliot EJ, Bower C. Prenatal Alcohol Exposure and Risk of Birth Defects. Pediatrics. 2010; 126 (4): 619-622. doi: 10.1542/peds.2010-1793
- Kesmodel, US, Bertrand J, Stovring H, Skarpness B, Denny CH, Mortensen EL, the Lifestyle During Pregnancy Study Group. The effect of different alcohol drinking patterns in early to mid pregnancy on the child’s intelligence, attention, and executive function. BJOG. 2012; 119:1180–1190. doi: 10.1111/j.1471-0528.2012.03393
- Anderson BL, Dang EP, Floyd RL, Sokol R, Mahoney J, Schulkin J. Knowledge, opinions, and practice patterns of obstetrician-gynecologists regarding their patients’ use of alcohol. Journal of Addiction Medicine. 2010; 4 (2):114-21. doi: 10.1097/ADM.0b013e3181b95015
- Crawford-Williams F, Steen M, Esterman A, Fielder A, Mikocka-Walus A. “My midwife said that having a glass of red wine was actually better for the baby”: a focus group study of women and their partner’s knowledge and experiences relating to alcohol consumption in pregnancy. BMC Pregnancy and Childbirth. 2015; 15 (79). doi: 10.1186/s12884-015-0506-3
- Drinking Guidelines for Pregnancy and Breastfeeding. International Alliance for Responsible Drinking website. http://www.iard.org/policy-tables/drinking-guidelines-pregnancy-breastfeeding/ Page updated February 2016.
- National: Women warned not to drink alcohol in first 3 months of pregnancy: Glass of wine a week safe during later stages: NHS watchdog overturns earlier guidelines. Guardian [London, England] 26 Mar. 2008: 2. Business Insights: Global. Web. 1 Nov. 2017.
- Henderson J, Gray R, Brocklehurst P. Systematic review of effects of low–moderate prenatal alcohol exposure on pregnancy outcome. BJOG. 2007; 114 (3): 243-252. doi: 10.1111/j.1471-0528.2006.01163
- Moyer MW. To Drink or Not to Drink. Scientific American website. https://www.scientificamerican.com/article/to-drink-or-not-to-drink/ Published March 1, 2013.
- O’Leary C. Fetal Alcohol Syndrome Literature Review. National Expert Advisory Committee on Alcohol. Commonwealth of Australia. 2002 https://www.flourishpaediatrics.com.au/docs/fnational-drug-straegy-fetal-alcohol-syndrome-a-literature-review-etalcsyn.pdf Accessed: 1 Nov. 2017.
- Sulik KK, O’Leary-Moore SK, Riley EP. Better Safe than Sorry. BJOG. 2012; 119 (10): 1159-1161. doi: 10.1111/j.1471-0528.2012.03434
16. Alcohol Use in Pregnancy. Centers for Disease Control and Prevention website. https://www.cdc.gov/ncbddd/fasd/alcohol-use.html Page last reviewed and updated July 21st, 2016.