Is it okay for women to drink alcohol while pregnant?

Is it okay for women to drink alcohol while pregnant? Last year a major Irish study – led by Dr Ciara Reynolds of Dublin's UCD Centre for Human Reproduction, Coombe Women and Infants University Hospital – contributed to a debate which is more nuanced than one might expect.

The fetal alcohol syndrome (FAS) as a medical diagnosis stems from a report in the Lancet journal (1973), when American paediatricians announced what "seems to be the first reported association between maternal alcoholism and aberrant morphogenesis in the offspring."

They investigated eight children from three ethnic groups, finding “a similar pattern of craniofacial, limb and cardiovascular defects associated with prenatal-onset growth deficiency and developmental delay.”

But Prof Elizabeth M Armstrong asserts that FAS was also regarded as a moral diagnosis, noting how the simplicity of moral categories contribute to their appeal: "If doctors cannot say with any degree of certainty how much alcohol is safe, how much unsafe in pregnancy, they can invoke Biblical authority where scientific expertise fails."

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Reynolds and colleagues contribute both to the FAS evidence base and the cultural context in which FAS is discussed. Writing in the European Journal of Obstetrics & Gynecology and Reproductive Biology, they cite the global consensus that pregnant women should neither drink excessively nor become intoxicated because of the risk of contracting FAS. However, they acknowledge that “the relationship between light maternal alcohol consumption and fetal outcome remains contentious and the professional advice women receive is conflicting.”

Their eight-year study (2010-2018) examined the relationship between fetal growth and maternal alcohol behaviour before and during early pregnancy by analysing the clinical and sociodemographic details of 68,925 women who each delivered a baby weighing 500g (1lb 2oz) or more. One-third abstained from drinking alcohol before pregnancy; 98.4 per cent reported abstinence at their first antenatal visit; only 1.2 per cent reported light consumption (1-2 units/week); 0.4 per cent reported moderate/heavy consumption (>3 units/week); and 0.3 per cent reported binge drinking (>5 units in one sitting).

Warnings about any alcohol in pregnancy mean that there has been a lack of focus on the real dangers

Importantly, in the absence of persistent smoking or illicit drug abuse there was no relationship between light alcohol consumption in early pregnancy “and aberrant fetal growth in the absence of persistent maternal smoking.”

With 98.4 per cent of women abstaining once they realised they were pregnant, and with 0.3 per cent reporting binge drinking, what are the implications of these findings from a public health perspective? The authors state: "However well intended, it is important . . . that reports on the rate of alcohol consumption during pregnancy in Ireland are not unduly alarmist."

Complete abstinence

Writing in support of guidelines which have found “no evidence of harm if women confine their alcohol intake to 1-2 units once or twice a week,” the authors suggest that advising complete abstinence from alcohol from conception until after delivery may be impractical, especially as one-third of all pregnancies in their study were unplanned.

Report co-author Prof Michael Turner is consultant obstetrician and gynaecologist at the Coombe Women and Infants University Hospital UCD Centre for Human Reproduction. He told The Irish Times of his difficulty with the message that women should not take any alcohol during pregnancy because, he says, it is potentially harmful and scientifically untrue: "The message has two important downsides. First, it generates unnecessary anxiety for pregnant women, especially if they took alcohol before their pregnancy test was positive.

“That anxiety may persist for the entire pregnancy until after they’ve delivered a healthy baby. If there’s an adverse outcome,” he added, “the mother may feel guilty even though the outcome may bear no relationship to alcohol. Second, warnings about any alcohol in pregnancy mean that there has been a lack of focus on the real dangers, which are persistent heavy drinking and binge drinking, in addition to the associated smoking and illicit drug use.”

Prof Turner comments that “women who have a glass of alcohol during pregnancy can be reassured that there is no scientific evidence that it is harmful to their baby.”

Some might argue that application of the “precautionary principle” (PP) favours wholesale abstinence. The PP derives from the German “Vorsorgeprinzip” or “foresight principle”, where governmental foresight is needed to prevent environmental risks and dangers. It was first used in the text of the 1985 Vienna Convention for the Protection of the Ozone Layer but has spread beyond its environmental origins to areas such as public health.

Public health practices should prioritise helping women to stop binge drinking or heavy drinking

Yet, in the context of evidence-based medicine, how does a “better safe than sorry” approach fit into a medical culture dedicated to proven scientific methods of risk evaluation? As Reynolds and colleagues indicate, if pure logic were followed, the PP “could be extended to other beverages women consume during pregnancy, for example, high-sugar drinks and caffeinated drinks. In clinical practice, adherence to a policy that links any prenatal alcohol exposure with increased fetal risks means that women who consume alcohol at any stage during pregnancy may be unnecessarily worried throughout pregnancy.”

In recommending that “public health practices should prioritise helping women to stop binge drinking or heavy drinking of alcohol before, during and after pregnancy,” Prof Turner’s approach derives from an assessment of available evidence rather than one that assumes the moralistic dimension identified by Prof Armstrong above.

Ethicist Dr Jillian Gardner noted in 2016 that "myriad . . . factors influence a woman's decision to drink and consequently contribute to poor pregnancy outcomes . . . (including older age at pregnancy, polydrug use, low socio-economic status, poor nutritional status and genetics)."

Finally, with society currently engaged with the Covid-19 crisis, Prof Turner stresses “the importance of continuing to provide health and support to those pregnant women whose addictions include alcohol.”