Alcohol and pregnancy: The evidence

The question of alcohol consumption during pregnancy is always a difficult one. Australian government recommendations are for no consumption of alcohol during pregnancy yet many women argue that this is overcautious and reflects a lack of judgement in other women rather than a real danger. My personal experience is that many women believe that these guidelines do not apply to them or their drink of choice (wine). This is reflected by current drinking rates during pregnancy being between 47-59 percent.  While it is true that the change in Australian guidelines from low level to no drinking, is not based on substantial new evidence but rather on a reinterpretation of existing evidence this does not necessarily make it poor advice.
Part of the issue, I believe is the lack of information regarding possible effects of low level drinking. People know of the danger of high level or binge drinking during pregnancy but all other information simply states not to drink rather than indicating what the potential effects could be.
Alcohol consumption during pregnancy can result in a large spectrum of harm. Alcohol crosses the placenta at almost the same level that it is consumed by the mother. High volume drinking is linked to birth defects but outside of this there is a wide variation of effects that can occur. The effects are influenced by the stage of development of the foetus at the time of exposure (being most vulnerable structurally in the first six weeks), characteristics of the mother including   age, parity, body composition, nutrition, other drug use, cigarette use, socio-economic status, education and genetics of both the mother and the foetus. The effect of genetic factors may be completely unknown to the mother and so impossible for her to predict the outcome.
Below are a list of the known effects of prental alcohol consumption from high to low level consumption.

  • High level or frequent intake of alcohol increases the risk of miscarriage, stillbirth and premature birth.
  • Foetal alcohol spectrum disorder results from high levels of alcohol in utero. People with foetal alcohol spectrum disorder have birth defects, impaired growth and abnormal central nervous system functioning  resulting n lifelong learning difficulties, increased mental illness and social problems.
  • Delinquent behaviour, reduction in verbal IQ, learning difficulties and poor educational performance  have been are more likely in children whose mother's binge drank (6+ drinks on one occasion) during pregnancy with risk increasing with higher frequency of binges.
  • Drinking more than five drinks on one or more occasion was associated with decreased cognitive ability with effect increasing with increasing frequency of heavy drinking.
  • Drinking 4 or more drinks per occasion in the second trimester linked to problems in reading comprehension and teachers' rating of poor school performance.
  • Small for gestational age was associated with intake of more than 3.6 standard drinks per day during pregnancy with the greatest effect in the first trimester.
  • Children exposed to binge drinking showed greater social disinhibition than children who were not.
  • 14 year olds who had been exposed to three or more drinks per week in the first trimester showed decreased weight, height, head circumference and skin fold thickness than those who weren't.
  • Increased rate of miscarriage has been found in women who drink between two and 14 standard drinks per week.
  • Likelihood of developing early-onset alcohol abuse disorder at between 13 and 17 years of age is higher when exposed to three or more standard drinks in early pregnancy.
  • A negative dose dependant effect on mental development in children aged 12-13 months was found when prenatal intake was higher than two drinks per day
  • Neurological effects including reduction in nerve conduction velocity and amplitude, decrease in visual acuity and reduction in the size of the frontal cortex has been found from intakes starting at two standard drinks per day.
  • Decrease on children's learning and memory score at 10 years of age at three or more drinks per week.
  • Problems with verbal learning and memory at 14 years of age at three or more drinks per week.
  • Decreases in working memory and executive functioning at age 7.5 particularly for numeracy was found from 1.4 standard drinks per day, with effects increasing with increasing alcohol consumption and maternal age.
  • Prenatal exposure of 1.4 standard drinks per week predicted lower IQ scores and deficits in mathematics in teenagers of lower socioeconomic status.
  • Average intake of 1.2 standard drinks per day increased the risk of low birth weight with a greater effect for smokers. This effect was not seen when drinking was infreqeunt.
  • Drink at low levels (less than one drink per day) in the first and second trimester linked to poorer rating of overall school performance at 10 years of age in women of lower socioeconomic status.
  • Any prenatal alcohol exposure was linked with higher likelihood of problem behaviours in children aged 6-7 years.
  • Risk of developing alcohol abuse disorder after the age of 18 was higher when there was alcohol exposure in early pregnancy.

All information from:


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