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Evidence linking alcohol, FAS and FASD

What is the evidence on prenatal alcohol exposure and the occurrence of FASD?

International studies confirm that the actual country prevalence of FAS and FASD is directly related to the population consumption of alcohol expressed in litres per person per annum.

There is strong proof that prenatal alcohol is the cause of FAS and FASD.

The association between prenatal alcohol exposure and FAS and FASD is strong.  This association is consistent from study to study, in all countries where it has been studied, in all nationalities and ethnic groups and in all socio-economic groups.  

The temporal relationship is correct in that the cause precedes the effect. 

A consistent dose-response gradient has been found

The more heavily the woman drinks during pregnancy the more likely the fetus will be affected. 

The association makes epidemiological sense.  As women drink more in society, the occurrence of cases of FAS and FASD has increased. 

The association makes biological sense as alcohol has long been established as having an adverse effect on the developing brain, and on body organs.  The association is specific. 

Prenatal alcohol exposure is the only known cause of the characteristic condition known as Fetal Alcohol Syndrome (FAS)

The association is analogous to a previously proven causal association.  The occurrence of teratogenicity was first realised when the Thalidomide tragedy unfolded.  Before Thalidomide, it was believed that the placenta was impervious to maternal drugs. Alcohol crosses the placenta and is a proven teratogen.

What is the Irish evidence of harm?

FASD diagnosis requires documented prenatal alcohol exposure.  This limits ascertainment.  Antenatal clinics do not test for alcohol. There is no Irish register of FASD, therefore the number of cases of FASD, FAS and ARND (Alcohol Related Neurodevelopmental Disorder) in Ireland is unknown.  FASD is also commonly misdiagnosed or unconfirmed. 


Irish studies on alcohol consumption during pregnancy, however, suggest the number of affected children in Ireland may be significant.

In January 2017, the Lancet published a review of alcohol consumption in pregnancy, the risk of FAS and the prevalence of people with FAS in the population¹  and estimated that about 600 Irish babies with FAS are born each year and that over 40,000 Irish persons have FAS.  This is the best estimate currently available.

 ¹Bradford Hill Sir Austin. The Environment and Disease: Association or Causation?  Proceedings of the Royal Society of Medicine, Section of Occupational Medicine Meeting January 14 1965

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