‘No safe limit’ – experts respond to alcohol during pregnancy research

New research suggests low and moderate drinking in early pregnancy is not associated with adverse neuropsychological effects in children, but Kiwi experts say the findings are “no reason for pregnant mums to pop the champagne”.

Danish researchers have produced a series of five papers looking at the effects of low, moderate, high and binge drinking on five year olds.

The papers, papers published this week in the journal BJOG: An International Journal of Obstetrics and Gynaecology, looked at the effects of alcohol on IQ, attention span, executive functions such as planning, organisation, and self-control in five year old children.

Overall, the researchers found that low to moderate weekly drinking in early pregnancy had no significant effect on neurodevelopment of children aged five years, nor did binge drinking.

However, high levels of alcohol intake – 9 or more drinks per week – was associated with lower attention span amongst five year olds.

A full press release and links to the articles (subscription only) are available here.

Although the researchers did not identify negative effects associated with low to moderate intake, they conclude in their final article, “safe levels of alcohol use during pregnancy have not yet been established. Consequently, women should be advised that it is safest to abstain from using alcohol when pregnant.”

Despite this caveat, some overseas media are reporting this study as proof that drinking in moderation during pregnancy is safe (for example Metro (UK) and the BBC). In response to such reporting the NHS in the UK has provided a critical analysis of the research.

The Science Media Centre contacted New Zealand experts for further comment:

Christine Rogan, Health Promotion Advisor (Coordinator of the Fetal Alcohol Network NZ), Alcohol Healthwatch, comments:

“These types of studies do not provide a reason for pregnant mums to pop the champagne!  Sadly though that is often the effect they have. The public (media) love good news headlines about drinking and the headline always wins, no matter the fine print such as the authors themselves conclude that no safe level of consumption has been established.

“My early look over the studies themselves and their findings:

  1. They are not methods that prove safety or disprove causation.  The children themselves were not tested. Rather their parents and teachers were asked to rate their observation of the child’s behavior.  At least the teacher’s had something to compare this with (other children) but these instruments are only ever able to detect gross differences in child behaviour.
  2. The study simply show that using these methods, ‘significant’ harm could not be detected from low levels of prenatal alcohol exposure.  Well one would expect that to be the case!
  3. It is impossible to predict the true genetic potential in any individual and equally impossible to say therefore that no harm has been done.
  4. On the contrary, what is very concerning (and a good reason to avoid alcohol during pregnancy) is that even using a generalized rating scale administered by parents/teachers, ‘significant’ effects began to be detected at 8+ standard drinks per week.   That is not an uncommon amount for NZ women to consume.  One study from Taranaki indicated that 66% of respondents were drinking at risky levels prior to pregnancy detection.
  5. Why would anyone think exposing a developing fetus to a proven teratogen – a neurotoxin would be okay?  There is no such thing as a ‘safe’ amount of alcohol for a fully mature adult only degrees of risk; the risk to adolescent brain development is recognized and delayed onset of drinking advised, so why expose children and unborn babies to it?
  6. The advice to avoid alcohol during pregnancy, when planning pregnancy and when breastfeeding remains the best, most valid and wise option for women to follow.  You know what they say about assuming…. Why risk that for the sake of your baby’s brain?”

Dr Sherly Parackal, Research Fellow, School of Population Health, University of Auckland, comments:

“The Danish researchers have published some interesting findings on the effects of low to moderate drinking and binge drinking during pregnancy on neuro-development at 5 years of age. The findings of this study needs to be assessed in the context of the drinking characteristics of the “reference group” both for “low and moderate drinking” and binge drinking.  The possibility that the reference group comprising of mothers who reported to be abstainers during pregnancy to have stopped alcohol consumption on recognition of pregnancy is quite high.  Which in other words mean that the reference group may have also drunk alcohol in early pregnancy.  For analyses pertaining to binge drinking the reference group is “Non-binge drinkers”. This group also comprised of some heavy drinkers.  Average drinks per week as used in this study do not reflect patterns of alcohol consumption, i.e. frequency and quantity.

“Even if the methodology employed is robust and the findings are generalizable these findings do not rule out any harmful effects of alcohol consumption in early pregnancy. Another team of researchers have used the same data set to investigate the effect of moderate drinking on fetal death. This study found an increased hazard ratio for fetal death in early pregnancy for 2 drinks or more a week and highlights the potential lethal effects of drinking in early pregnancy.

“The prudent recommendation is to not drink any alcohol during conception and in pregnancy and if a women has unintentionally drunk some alcohol prior to pregnancy recognition, stopping on pregnancy recognition would be beneficial both for the mother and baby”

Prof Jennie Connor, Head of Department, Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, comments:

“The detrimental effects of being exposed to heavy drinking in utero on cognitive function and behaviour in children is well documented. It is difficult to study drinking in pregnancy because of the difficulties of getting good measures of intake in situations where such behaviour is stigmatised. This Danish study is an important addition to our understanding, and suggests that very low volumes of drinking do not have effects on child development that are detectable using a selection of standard tests at age 5.

“There is a risk that this information could lead women to believe that it is reasonable to drink during pregnancy as long as it is not “too much”. There are a number of reasons to be very cautious:

  • This research does not establish a safe level of drinking, as the authors themselves point out.
  • The alcohol intake that was associated with no untoward effects being observed  (up to 8 drinks a week) is very low. When you allow for the fact that these are 12g drinks, this is equivalent to almost 10 drinks in NZ or Australia, which is well within the Australian low risk drinking guideline of no more than 14 drinks per week.The children of mothers who had 9 or more drinks per week were  observed to have some reduction in attention spans, so this included mothers under the low risk drinking guideline.
  • From the point of view of preventing harm to children from drinking, the most important goal is to reduce the incidence of heavy drinking in pregnancy. The most effective way to achieve this will be to reduce binge drinking in the population in general (to reduce early exposure), and for abstention in pregnancy to be the accepted norm. Any messages about the “safety” of drinking in pregnancy will be counterproductive, and are not justifiable as no safe level has been identified.

“It would be difficult to reproduce this study in NZ even though drinking in pregnancy is common, because it is not as acceptable as in the Danish population and therefore difficult to measure well. It is not necessary to conduct this kind of research in NZ, as the biological mechanisms of harm are likely to be identical.

“What would be useful in NZ is regulation of the drinking environment to reduce volumes of alcohol consumed and frequency of drinking across the whole population, coupled with strategies to promote non-drinking households during pregnancy, and focusing on the value of abstaining from alcohol, smoking and other drugs in order to give babies the best possible start in life.”

Assoc. Prof Kathryn Kitson, Institute of Food, Nutrition and Human Health, Massey University, comments:

“The report on this study should be that ‘as little as 9 drinks per week shows association with an increased risk of attention problems in children.’ This result endorses the recommendation of no drinking in pregnancy if a cautious safety recommendation (e.g. of 1000 fold or less levels of exposure to a toxin below the limits that indicate damage) is applied. A ‘safe’ limit should be around 0.009 drinks per week – i.e. essentially no alcohol at all.

“Alcohol is a teratogenic agent that alters fetal development via interference with the intricate mechanisms that regulate switching genes on and off at critical developmental stages. This includes regulation of the neuronal linkages that are formed during development of the brain.

“There is no known safe limit for drinking in pregnancy, and the results of this study actually endorse that message, if correctly reported.”