Advice to cut all drinking during pregnancy based on ‘generally weak’ evidence

Experts have welcomed a review that has found very limited evidence that light drinking in pregnancy harms unborn babies.

They said Government recommendations that women stop drinking altogether in pregnancy was based on “generally weak” evidence.

Some said women should be informed of any potential risk and left to make up their own minds.

Drinking during pregancy
(Anthony Devlin/PA)

In the new review, researchers found very little evidence that light drinking in pregnancy causes harm to babies, including birth defects, developmental delay, behavioural problems and impaired intelligence.

However, they warned that a lack of evidence is not proof that it is fine to drink, and they recommended pregnant women do not drink alcohol as a “precautionary” measure.

Official NHS guidance from the Chief Medical Officers for the UK published last year says pregnant women should not drink because “experts are still unsure exactly how much – if any – alcohol is completely safe for you to have while you’re pregnant”.

It adds: “Drinking in pregnancy can lead to long-term harm to the baby, with the more you drink, the greater the risk.”

Pregnant woman
(Katie Collins/PA)

Up until last year, women were told they could drink up to one or two units, once or twice a week.

The new research review, published in the journal BMJ Open, was undertaken by experts from the Medical Research Council’s Integrative Epidemiology Unit at the University of Bristol, the University’s School of Social and Community Medicine, and University Hospitals Bristol NHS Foundation Trust.

They trawled all available research on the effects of light drinking in pregnancy (up to four units of alcohol per week).

One unit is 8g of alcohol – equivalent to half a pint of beer, lager or cider at 3.5% strength, a single measure (25ml) of spirits, such as whisky, gin, rum or vodka, or half a standard (175ml) glass of wine at 11.5% strength.

The team examined 26 available studies on the issue.

Red wine being poured into a stem glass at the table

They found that drinking up to four units a week while pregnant, on average, was associated with an 8% higher risk of having a small baby compared with drinking no alcohol at all.

There was also a potential risk linked to premature birth, although this was less clear.

Very few studies compared light to non-drinkers, and there was a distinct lack of evidence on most other outcomes for the baby, including development, behaviour, cognitive impairment, greater problems in pregnancy or a more complicated delivery.

The researchers said there was insufficient data to “make robust conclusions”, adding that evidence on the effects of light drinking was “sparse”.

Pregnant woman holds a glass of wine

They called for more research on light drinking in pregnancy, including possible benefits of light alcohol consumption versus abstinence.

But they added: “However, describing the paucity of current research and explaining that ‘absence of evidence is not evidence of absence’, appears warranted.”


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