Alcohol Drinking During Pregnancy
Critique 207: Effects on birth weight and risk of preterm birth of light-to-moderate drinking during pregnancy – 2 November 2017
Reference: Strandberg-Larsen K, Poulsen G, Bech BH, Chatzi L, Cordier S, et al. Association of light-to-moderate alcohol drinking in pregnancy with preterm birth and birth weight: elucidating bias by pooling data from nine European cohorts. Eur J Epidemiol 2017 pre-publication; DOI 10.1007/s10654-017-0323-2
There is no question that high levels of alcohol consumption during pregnancy can lead to severe adverse effects on the fetus, with the most serious condition known as fetal alcohol syndrome (FAS). Many studies have also related alcohol intake during pregnancy with premature birth, low birth weight, and the infant being small for gestational age (SGA). Data are not as clear on the effects just of occasional or light drinking, but most studies have not detected adverse effects.
The present paper, based on a pooled sample of almost 200,000 women from nine European cohorts, provides data indicating that premature birth, an infant being small for gestational age (SGA), or being of low birth weight do not appear to be associated with light-to-moderate intake (up to 6 drinks/week); these results are similar to those from many other recent studies. In this large study, mothers who consumed greater amounts of alcohol tended to have an increased risk of the infant being SGA or with low birth weight, but such a level of drinking had no effect on the risk of premature delivery. This cohort consisted almost exclusively of light drinkers; no data were available on other potentially harmful effects of excessive drinking.
An interesting additional finding was that the reported frequency of any alcohol consumption during pregnancy in the cohorts studied has decreased dramatically in recent decades (from approximately 50% of women studied prior to 2000, to 39% in 2000-2004, to 14% in 2005-2011). This suggests that most women are responding to guidelines recommending that a woman not drink during pregnancy.
Based on currently available information, the Forum considers that a recommendation to “avoid alcohol during pregnancy” is appropriate as part of drinking guidelines for the public. However, scientific data, including the present paper, do not suggest that women who may have an occasional drink or very light alcohol consumption during pregnancy should have undue concern about having a premature birth or a low-birth-weight infant.
For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.
Critique 151: “Fetal alcohol syndromes” result from multiple maternal factors during pregnancy — 20 November 2014
Reference: Esper LH, Furtado EF. Identifying maternal risk factors associated with Fetal Alcohol Spectrum Disorders: a systematic review. Eur Child Adolesc Psychiatry (2014) 23:877–889; DOI 10.1007/s00787-014-0603-2.
Excessive maternal alcohol consumption during pregnancy (especially among women with alcohol dependency) is known to markedly increase the risk of the fetus showing a group of developmental disorders defined as fetal alcohol spectrum syndrome (FASD), with the most serious form being fetal alcohol syndrome (FAS). The present paper attempts to identify maternal risk factors for FASD and FAS, but the authors report that there were not enough data to carry out a formal meta-analysis. They do, however, describe important maternal risk factors that have been reported in the literature to relate to these syndromes. The more frequent maternal conditions related to the risk of FASD or FAS include older age of mother, lower educational level, family relatives who abuse alcohol, little prenatal care, and a more severe pattern of alcohol consumption in general and particularly during pregnancy. They emphasize that “FAS is a multifactorial condition, and it is potentiated by complex relationships among several factors, social and biological.”
Forum reviewers considered this to be a well-done analysis presenting important and balanced information on these syndromes. Forum members agreed that many genetic and environmental factors, in addition to heavy alcohol consumption, may contribute to the development of these syndromes (e.g., certain genetic polymorphisms, inadequate pre-natal care, poverty, low education, familial alcoholism, use of illicit drugs, etc.).
Given the permanent nature of many of the defects found in FASD and FAS, and limited therapeutic options, it is important that the focus should be on the prevention of these syndromes. If they are to be prevented, it will be necessary to intervene among high-risk women, either prior to or early during pregnancy. Better knowledge of all the factors involved will help facilitate interventions that may help prevent these serious conditions.
For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.
Critique 137: Alcohol intake prior to and during pregnancy and birth outcomes — 28 March 2014
Reference: Nykjaer C, Alwan NA, Greenwood DC, Simpson NAB, Hay AWM, White KLM, Cade JE. Maternal alcohol intake prior to and during pregnancy and risk of adverse birth outcomes: evidence from a British cohort. J Epidemiol Community Health 2014, pre-publication. doi:10.1136/jech-2013-202934
The present analysis was carried out among 1,264 women from Leeds, UK, whose alcohol intake was estimated prior to and during pregnancy. The outcomes were birth weight of the infant and whether or not it was small for gestational age (SGA). In comparison with most previous research on this topic, this study is notable for being of a relatively small size. Further, it had a high percentage of women who consumed alcohol both prior to and during the first trimester, had a very low participation rate of eligible women (only 30%), failed to present estimated effects by ethnicity, and had some questions related to residual confounding. It is unclear how the results of this study increase our knowledge of maternal alcohol consumption and birth outcomes.
Forum members do not believe that the consumption of alcohol should be recommended for pregnant women. A certain percentage of newborns will be small for gestational age, have certain deformities, and have later emotional and behavioral abnormalities. If a woman has consumed any alcohol during the pregnancy, she (and perhaps even her doctor) may blame the abnormality on alcohol consumption, whether or not it had anything to do with it. Hence, the majority of Forum members agree that women should not be encouraged to consume alcohol during pregnancy.
Further, scientific data are very consistent on the potential risks of serious adverse health outcomes of the infant from heavy maternal drinking, especially among women who are alcoholics. Heavy-drinking women who become pregnant should be strongly urged to stop their drinking.
On the other hand, sound data indicating harmful effects on the fetus of light or occasional drinking by a pregnant woman are difficult to come by. Because of the epidemiologic concerns of the present paper, described in our Forum critique, we do not believe that this study adds materially to our understanding of the topic. The serious anxiety occurring among some women who may have ingested some alcohol prior to learning that they were pregnant seems, based on numerous studies, to generally be unnecessary; the need to abort a fetus because of previous light drinking by the mother cannot be justified.
There is a serious problem in interpreting all studies of prenatal alcohol exposure and the outcomes of pregnancy because of potential confounding, especially by ethnicity, education, smoking, coexisting use of illegal drugs, etc. Further, alcohol use by pregnant women has become an especially emotional and even a moral issue, and the entangled confounders make rational analysis most difficult. This means that there is a difficult challenge for epidemiologists and statisticians, as well as for public health officials and the general public, about how to interpret results of individual research projects. The literature can support varying views, from no alcohol at all for those who might soon be expectant mothers to being able to drink moderately throughout pregnancy.
Also, it should be pointed out that the potential health benefits of moderate alcohol consumption relate primarily to middle-aged and older people, so there is no reason for pregnant women to consume alcohol for its “health effects.” Thus, it is very reasonable that the majority of women choose to avoid alcohol during pregnancy. Further, heavy drinking during pregnancy has known potentially serious consequences, and should never be encouraged. Finally, there is insufficient scientific evidence that an occasional drink of alcohol during pregnancy leads to harm to the fetus, and should not cause undue alarm in a pregnant woman who may have consumed some alcohol before she realized she was pregnant.
For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.
Critique 107: Little effect on child’s mental functioning associated with mother’s light, occasional drinking in early pregnancy – 25 March 2013
Reference: Sayal K, Draper ES, Fraser R, Barrow M, Davey Smith G, Gray R. Light drinking in pregnancy and mid-childhood mental health and learning outcomes. Arch Dis Child 2013;98:107–111. doi:10.1136/archdischild-2012-302436.
A new report from the prospective, population-based Avon Longitudinal Study of Parents and Children (ALSPAC) in the UK is based on investigation of the association between light drinking in pregnancy (<1 glass per week in the first trimester) and child mental health. Mental health was assessed in more than 6,000 children using both parent- and teacher-rated Strengths and Difficulties Questionnaires (SDQs) at age 11 years. Academic outcomes based on Key Stage 2 examination results were measured in more than 10,000 children.
Approximately 40% of women consumed some alcohol but less than 1 glass/week, while 16% reported consuming ≥1 glass per week during the first trimester. The authors report that after adjustment, relative to abstainers, there was no effect of light drinking on teacher-rated scores or examination results. In girls, although there was a suggestion of worse outcomes on the parent-rated total score in those exposed to light drinking compared to abstainers, no dose–response relationship was evident. The authors conclude: “Light drinking in pregnancy does not appear to be associated with clinically important adverse effects for mental health and academic outcomes at the age of 11 years.”
Forum reviewers considered this to be a well-done study, with a balanced assessment of results by the authors. Reviewers were surprised at the somewhat arbitrary separation of alcohol consumption: <1 drink per week versus ≥1 drink per week. Current guidance about alcohol consumption in pregnancy from the Department of Health in England (2009) allows for pregnant women to drink up to 1–2 units of alcohol once or twice a week, and it would have been preferable to have data presented for drinkers at this level.
Forum Co-Director Conibear considered that “The most important aspect of this study relates to the fact that 25% of babies in the UK are unplanned, and 17% of mothers do not know they are pregnant until eight weeks or more. Therefore balanced advice concerning the effect of alcohol use in early pregnancy is crucial to prevent unnecessary concern amongst this group of mothers to be. Although the best advice is to avoid alcohol if you are pregnant, the present research can reassure mothers who drank occasionally without realising that they were pregnant that they have not done long-term harm to their baby.”
Forum reviewer Stockley added: “I think that another important message is that if a woman decides to consume a small amount of alcohol during pregnancy, she should never binge drink or get drunk. This we know can have adverse effects on the developing fetus, especially in the first trimester, but interestingly, also in the third trimester of pregnancy.”
For the full critique of this publication by members of the International Scientific Forum on Alcohol Research, please click here.
Critique 050: Multiple maternal risk factors for fetal alcohol disorders – 7 August 2011
An extremely well researched and written review on the relation of maternal drinking during pregnancy to adverse fetal outcomes has been published by scientists from the University of New Mexico Center on Alcoholism, Substance Abuse, and Addictions. It covers many factors (host, agent exposure, and environment) that have been found to relate to the occurrence of fetal alcohol spectrum disorders (FASD). Such factors modify the risk associated with alcohol consumption during pregnancy, although the risk of abnormalities is clearly increased with frequent consumption of large amounts of alcohol, and is greater among women who are alcoholics. While current data do not show that light or occasional alcohol consumption during pregnancy increases the risk of FASD, Forum members do not believe that pregnant women should be encouraged to drink.
Forum members agree with the authors that “More research is needed to more clearly define what type of individual behavioral, physical, and genetic factors are most likely to lead to having children with FASD.” Evaluating these multidimensional factors should help identify women at particular risk for having a child with FASD and lead to interventions to prevent such fetal abnormalities.
Reference: May PA, Gossage JP. Maternal risk factors for fetal alcohol spectrum disorders. Not as simple as it might seem. Alcohol Research & Health 2011;34:15-26.
For the full critique of this article by members of the International Scientific Forum on Alcohol Research, please click here.
Critique 020. New data on effects of alcohol during pregnancy. 12 October 2010
Reference: Kelly YJ, Sacker A, Gray R, Kelly J, Wolke D, Head J, Quigley MA. Light drinking during pregnancy: still no increased risk for socioemotional difficulties or cognitive deficits at 5 years of age? J Epidemiol Community Health 2010; doi:10.1136/jech.2009.103002.
A very large population-based observational study from the UK found that at the age of 5 years, the children of women who reported light (no more than 1-2 units of alcohol per week or per occasion) drinking did not show any evidence of impairment on testing for behavioral and emotional problems or cognitive ability. There was a tendency for the male children of women reporting “heavy/binge” drinking during pregnancy (7 or more units per week or 6 or more units per occasion) to have poorer behavioral scores, but the effects were less clear among female offspring.
Scientific data continue to indicate that higher intake of alcohol during pregnancy may adversely affect the fetus, and could lead to very severe developmental or other problems in the child. However, most recent publications (as does this one) show little or no effects of occasional or light drinking by the mother during pregnancy. They also demonstrate how socio-economic, education, and other lifestyle factors of the mother may have large effects on the health of the fetus and child; these must be considered when evaluating the potential effects of alcohol during pregnancy.
Overall, current scientific data indicate that while drinking during pregnancy should not be encouraged, there is little evidence to suggest that an occasional drink or light drinking by the mother is associated with harm. Heavy drinking, however, may be associated with serious developmental defects in the fetus.
For the full critique of this paper by the International Scientific Forum on Alcohol Research, please click here.
Addendum: After the above critique was prepared, a new paper has been published on the topic by O’Leary et al (O’Leary CM, Nassar N, Kurinczuk JJ, de Klerk N, Geelhoed E, Elliott EJ, Bower C. Prenatal Alcohol Exposure and Risk of Birth Defects Pediatrics 2010;126;e843-e850; DOI: 10.1542/peds.2010-0256). Overall, the results of that study are similar to those of the study by Kelly et al, with no increase in risk of birth defects in children born of women reporting low or moderate drinking during pregnancy but with an increased risk of defects among children of women reporting heavy drinking.