Alcohol consumption during pregnancy, risks at low consumption

The current recommendation to pregnant women in Sweden, and in many other countries, is to abstain from alcohol throughout the pregnancy. Nevertheless, about 30 children with severe alcohol-related effects are born annually in Sweden (data from 2006–2013). Thus, there is a great need of communicating knowledge and advice to pregnant women about alcohol consumption and related risks to the unborn child.
The current report summarises the scientific literature (published from 2008 and onwards) regarding low to moderate alcohol consumption during pregnancy and related risks to the unborn child. The aim of the report is to answer specific questions, such as if very small amounts of alcohol (in e.g. food) can cause a risk. In total, 37 publications with epidemiological studies (original studies) have been included, with several studied effects from low prenatal alcohol exposure. A few studies with animal models have also been included. No studies where the effects from consumption of very low amounts of alcohol, present in food from e.g. cooking with alcohol as an ingredient or in beverages that contains alcohol levels below 1.2 percent by volume, have been identified.
One adverse effect that is mainly associated with high consumption of alcohol, but which can also appear at lower consumption, is fetal alcohol syndrome (FAS), which includes facial dysmorphia in combination with growth deficiency and abnormalities of the central nervous system (CNS). Alcohol exposed children (in utero) can also be affected by growth deficiency and preterm birth as well as impaired cognition and behaviour (abnormalities of the CNS) without having the characteristic facial features. All effects are collected under the umbrella term ‘fetal alcohol spectrum disorders’ (FASD). An increased risk for miscarriage is also associated with alcohol consumption. Alcohol is a teratogen, which is an external factor that can cause birth defects. Teratogenic effects associated with alcohol can appear at any time during pregnancy; no period is safe. The same type of adverse effects can be observed in both animal models and in humans.
In the scientific literature with studies of effects associated with low prenatal alcohol consumption there are large uncertainties about what the lowest dose is for teratogenic effects to occur. Studies of the same outcome after about the same amount of consumed alcohol result in contradictory conclusions, with both positive and negative observations, that is that some studies demonstrate an adverse effect of the child, while others cannot show any effect. A probable cause for the various conclusions is the choice of different study designs, with for example differences in classification of dose groups, evaluation methods and how confounding factors have been adjusted for. Examples of confounding factors are demography, socioeconomic status, age and education. Also, genetic factors can contribute to individual sensitivity, something that is not generally investigated in the included studies.
The discrepancy between the results from the studies, as well as individual sensitivity, imply that a reliable limit for a safe consumption of alcoholic beverages during pregnancy cannot be determined. The risk for negative effects on the child will likely increase with increased alcohol consumption. From studies where food has been cooked (heated) with alcohol (beer or wine) it is shown that the alcohol concentration in one portion is very low, and accordingly give a low exposure and probably a very low risk. The same apply to consumption of beverages that contains alcohol concentrations below 1.2 percent by volume.

Link to report

Note: this report is published by the Swedish Food Agency as part of their SLV-Report Series (ISSN: 1104-7089).