Published On: Tue, Sep 12th, 2017

Pregnant? It’s okay to drink two glasses of wine a week says study | Health | Life & Style

The evidence that light or occasional drinking in pregnancy was harmful was “surprisingly limited” but scientists advised expectant mums are advised to avoid alcohol “just in case.” 

This was because there was a small risk of having an underweight or premature baby if the woman drank up to four units in a week. 

Previous studies have shown heavy drinking during pregnancy cause birth defects, affect the baby’s intelligence and lead to behavioural, mental and fine motor problems. 

As a result women are told to avoid heavy or ‘binge drinking’ but advice on “safe” drinking levels remains a grey area. 

Until recently UK guidelines advised women to avoid drinking alcohol while trying to conceive, and in the first trimester. 

At the same time it indicated that consumption should be restricted to within ‘one to two UK units, once or twice a week.“ 

However new guidelines from the UK Chief Medical Officer recommended women should not drink any alcohol at all while trying to conceive or while pregnant, on the grounds that it is “better to be safe than sorry.“ 

But this has left many women confused about whether there a safe limit and if just one glass was harmful. 

The issue remains of great public health importance because up to 80 per cent of mums-to-be in the UK, Ireland, New Zealand and Australia drink some alcohol during their pregnancy. 

So Bristol University scientists set out to determine the effects of low-to-moderate levels of drinking by women on pregnancy and the long-term health effects on their child. 

The study carried out a systematic review of 5,000 studies and selected 26 which looked at the impact of light drinking of two units up to twice a week, or four units a week, equivalent to a total of around 32 g compared with no alcohol at all. 

It looked particularly at complications of pregnancy and birth characteristics, such as miscarriage, premature birth, and undersized babies, and longer term issues, such as the developmental delays, impaired intellect and behavioural difficulties typical of foetal alcohol syndrome – consequence of heavy drinking in pregnancy. 

It found drinking up to four units a week while pregnant, on average, was associated with an eight per cent higher risk of having a small baby, compared with drinking no alcohol at all. 

Likewise drinking up to four units or 32g a week was associated with an 10 per cent increased risk of premature birth. 

The study noted in comparison, light to moderate smoking of less than 20 cigarettes per day was associated with a 22 per cent increased risk. 

But the evidence on how much, if any, is safe to drink, or at what stages of pregnancy, is notable by its absence. 

Senior Research Associate Dr Loubaba Mamluk said: “In conclusion, we found limited evidence for a causal role of light drinking in pregnancy, compared with abstaining, on most of the outcomes examined. 

“Despite the distinction between light drinking and abstinence being the point of most tension and confusion for health professionals and pregnant women and contributing to inconsistent guidance and advice now and in the past, our extensive review shows that this specific question is not being researched thoroughly enough, if at all. 

“In addition, there has been no evidence regarding possible benefits of light alcohol consumption versus abstinence. 

“Formulating guidance on the basis of the current evidence is challenging. 

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

“Women who have had a drink while pregnant should be reassured that they are unlikely to have caused their baby considerable harm, but if worried, they should discuss this with their GP or midwife. 

“Evidence of the effects of drinking up to 32 g/week in pregnancy is sparse. 

“As there was some evidence that even light prenatal alcohol consumption is associated with being underweight and preterm delivery, guidance could advise abstention as a precautionary principle.” 

A standard 175ml glass of red, white or rose wine with a ABV of 12 per cent contains 2.1 units. 

The study was published in the journal BMJ Open. 

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