18 May 2015
Healthcare professionals are still unsure of how much alcohol is safe for a pregnant woman to drink. Here, leading psychologist Professor Peter Hepper, [Belfast] who is renowned for his research into the effects of alcohol on babies, gives his expert advice
DRINKING during pregnancy may have long-term consequences for the developing foetus, impairing their behavioural, social or cognitive functioning after birth.
These effects are due to alcohol influencing the development and functioning of the individual’s brain and nervous system.
In some cases exposure to alcohol may also result in physical, growth and organ abnormalities, also known as Foetal Alcohol Syndrome.
The British Medical Association in 2007 estimated that one in 100 live births are adversely influenced by exposure to alcohol and 1 in 1,000 display Foetal Alcohol Syndrome.
These adverse consequences are often only detected some years after birth.
Our research, examining the behaviour of the human foetus, offers the opportunity to document the effects of alcohol in real time and at the time when alcohol is influencing brain and how it works.
The behaviour of the foetus can be defined as any observable movement or reaction to an external stimulus (eg startling to the sound of a loud noise) of the foetus.
The foetus can be observed safely using ultrasound to provide detailed observations of even the smallest movements, such as the opening and closing of the pupil of the eye, or twitches in response to a sound.
As behaviour is a product of the brain, examining behaviour enables how the brain is working to be assessed.
Thus the effects of alcohol on the brain of the foetus may be seen in changes in its behaviour.
Studies have attempted to observe the effects of alcohol on the foetus.
First, mothers have been asked to drink a small amount of alcohol and its effect on the behaviour of their foetus observed.
Second, the behaviour of foetuses of mothers who drink alcohol has been compared with the behaviour of foetuses whose mothers did not drink alcohol.
When observing the foetus following the mother drinking alcohol – small amounts, just the equivalent of one or two glasses of wine – the foetus’ breathing movements stop.
These breathing movements are not to inspire air but rather practising the movements for when the foetus is born and breathing is essential for survival after birth.
Movements decrease almost immediately upon maternal consumption of alcohol and have disappeared totally by 30 to 40 minutes after consumption.
Between two and three hours later movements are still absent despite maternal blood ethanol levels reading zero at this time.
The behavioural states of the foetus are also disrupted.
When comparing the behaviour of the foetus of mothers who drink against foetuses of mothers who do not drink, when there is no alcohol in the mother’s blood stream, indicates spontaneous startles occur more frequently in fetuses whose mothers drank low levels of alcohol – approximately 2.5 units a week – than in foetuses of mothers who didn’t drink alcohol.
Similarly elicited startles, a movement response to the presentation of a loud noise, occur less frequently in foetuses exposed to alcohol compared to foetuses whose mothers do not drink.
These results may be explained by the fact that alcohol delays the development of the brain, causing spontaneous startles to persevere after the time that they would normally disappear but delaying the emergence of the elicited startle.
Studies have examined habituation, a form of learning, whereby the brain turns off attention to irrelevant events, such as sound, to enable focus on other potentially dangerous events.
This can be illustrated when we hear a ticking clock when first entering a room.
But after a brief period of time you no longer hear the ticking, even though it is still there.
Using a sound to elicit a “jump” in the foetus, it was found that binge drinking affected the foetus’ response and more sound presentations – or poorer learning – were required before the foetus stopped responding.
Furthermore, when tested on different occasions, there was much more variability in brain function in foetuses exposed to alcohol compared to foetuses not exposed to alcohol.
These studies indicate that alcohol, even a single glass, affects the brain of the fetus, influencing its behaviour. Given that the effects of alcohol exposure are entirely preventable, a clear consistent message should be provided by all that even a single glass of alcohol may affect the foetus.