Page last updated at 08:43 GMT, Friday, 31 October 2008

Q&A: Alcohol and pregnancy

Pregnant woman
Alcohol can damage a developing foetus
A large-scale study has been published showing no link between having the occasional drink during pregnancy and behavioural problems in the child.

What does the study say?

The work by researchers at University College London looked at almost 12,500 children.

Those whose mothers had had anything from an occasional drink to a maximum of two drinks a week during pregnancy - classed as light drinking - were not found to be at any increased risk of behavioural problems compared to those whose mothers abstained from alcohol.

They were even found to score more highly in some areas, such as vocabulary tests, when they were assessed at the age of three.

But the mothers tended to be better educated and from higher income families than those who abstained, and the researchers suggest these social factors may play a part in the results.

Does this change research existing guidance?


Government advice to women who are trying to conceive, or who are already pregnant, is that the safest course of action is to avoid alcohol altogether.

But if they do choose to drink, they should consume no more than one or two units of alcohol, once or twice a week - and should not get drunk.

There is some dispute however.

The British Medical Association warns the study findings may "lull" women into feeling drinking alcohol in pregnancy is safe.

It says moderate and heavy drinking are definitely not safe, and that the evidence is not conclusive on light drinking.

The Royal College of Obstetricians and Gynaecologists does not disagree that heavier drinking is dangerous, and says it would like to see the UCL study's findings confirmed in further research.

But it says the work suggests women should not be worried if they have had the odd drink while they are, or were, pregnant.

What impact does alcohol have on the unborn baby?

Alcohol can cross from the mother's blood via the placenta to the baby's circulation.

It is well established that heavy drinking during pregnancy can affect the development of the foetus.

The first three months, or first trimester, of pregnancy is particularly key, as this is the time when the organs and nervous system are rapidly developing.

Heavy alcohol consumption during the more advanced stages of pregnancy can also stymie general growth.

In particularly serious cases heavy drinking can lead to a condition known as foetal alcohol syndrome.

This a name given to a set of symptoms which can include facial abnormalities, such as small heads and widely spaced eyes, poor growth, impaired learning and memory skills and behavioural problems such as hyperactivity.

The National Organisation on Foetal Alcohol Syndrome estimates more than 6,000 UK children are born with Foetal Alcohol Spectrum Disorder each year.

Heavy drinking also significantly raises the risk of a miscarriage.

What about breastfeeding?

Doctors suggest that the occasional drink - again one to two units no more than once or twice a week - probably won't do any harm.

However, more heavy drinking can make breast milk smell different to a baby, potentially disrupting their feeding patterns.

There is also evidence that it can cause problems for a baby's digestion.

Alcohol clears from a mother's milk at the rate of around one unit every two hours. So try to avoid alcohol before breastfeeding, or plan ahead and express milk if you know you will be drinking.

How much is a unit of alcohol?

The measurement of alcohol units was recently revamped to take account of the modern trend for stronger drinks, and bigger glasses.

A half pint of normal beer and a single shot of a spirit is defined as a single unit, while a medium glass of 12.5% table wine is considered to contain two units.


Drink Volume Strength Units
Normal beer/lager/cider      
half pint 284ml 4 1
large can/bottle 440ml 4.50% 2
Strong beer/lager/cider      
half pint 284ml 6.50% 2
large can/bottle 440ml 6.50% 3
Table wine      
small glass 125ml 12.50% 1.5
medium glass 175ml 12.50% 2
large glass 250ml 12.50% 3
bottle 750ml 12.50% 9
single shot 25ml 40.00% 1
bottle 750ml 40.00% 30
bottle 275ml 5.00% 1.5

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