How much alcohol can you drink when you're pregnant?

Women who are pregnant or trying to conceive should avoid alcohol altogether.
UK Chief Medical Officers

This advice is precautionary. It's known that alcohol can pass from your bloodstream across your placenta to your unborn baby and, because a baby in the womb is not yet able to process alcohol effectively,¹ this can cause long-term harm. Studies^{1, 2, 3, 4, 5} have shown that potential harm is greater the more you drink and includes an increased risk of:

miscarriage
premature birth
your baby having a low birthweight
your baby having behavioural and learning difficulties
(if you drink heavily throughout pregnancy) your baby having a range of physical and mental disabilities known as 'fetal alcohol syndrome'

But what if you've already drunk alcohol because you hadn't realised you were pregnant? The guidelines go on to say that:

If you find out you're pregnant after already having drunk in early pregnancy, you should avoid further drinking. However, you should not worry unnecessarily, as the risks of your baby being affected are likely to be low
UK Chief Medical Officers

Both the UK's Royal College of Obstetricians and Gynaecologists⁶ (RCOG) and the American College of Obstetricians and Gynaeclogists⁷(ACOG) echo this reassurance that it's unlikely that your baby has been harmed. The experts at RCOG recommend talking to your midwife or GP, if you're worried, and the experts at ACOG advise you not to drink any alcohol for the rest of your pregnancy.

Find out more about drinking before you realise you're pregnant

So, drinking ANY amount of alcohol is harmful when you're pregnant?

Ah well, this is the bit that's not entirely clear.

We know that drinking alcohol in pregnancy can be harmful for an unborn baby – and that the risk of harm to your baby is greater the more alcohol you drink, and generally accepted to be higher in your 1st trimester.

There are plenty of studies that conclude this. A recent systematic review by University of Bristol researchers (Jan 2020),⁸ for example, found that alcohol exposure in the womb has a "likely causal detrimental role on cognitive outcomes [for babies], and... a role in low birthweight".

However, what we don't know for certain is how much alcohol we're talking about. It's actually pretty unclear at what point alcohol consumption becomes harmful: is it after the 1st mouthful, the 1st glass, the 3rd glass – or what? And are we only talking about regular drinking or is it harmful to your baby just to have the occasional drink, like a glass of champagne at a wedding?

There's a good deal of research about the harmful effects of regular, heavy drinking and of binge-drinking in pregnancy but there are fewer studies about lighter or occasional drinking in pregnancy– and, among those, there's little evidence that 'low or moderate' drinking while pregnant (mostly defined as 1 or 2 units, once or twice a week) causes harm to your baby.⁹

Of course, little evidence of harm is not the same as being sure there's no harm. Which is why the Chief Medical Officers – and many other experts – have taken the 'rather be safe but sorry' approach in recommending that you avoid alcohol completely.

Do all the experts agree that pregnancy should be 'alcohol-free'?

An awful lot of them, do, yes. But there are some, including those at the British Pregnancy Advisory Service (BPAS)¹⁰ and the maternal rights campaign group Birthrights,¹¹ who criticise the recommendation: they point out it's not evidence-based and is so strict, it could cause unnecessary worry.

"There can be real consequences to overstating evidence, or implying certainty when there isn’t any," says Clare Murphy, Director of External Affairs at BPAS. "Doing so can cause women needless anxiety and alarm – sometimes to the point that they consider ending an unplanned but not unwanted pregnancy because of fears they have caused irreparable harm [by drinking before they knew they were pregnant].

"It also assumes women cannot be trusted to understand risk and, when it comes to alcohol, the difference between low and heavy consumption."

What's the latest scientific evidence about drinking alcohol in pregnancy?

Drinking in your 1st trimester: not recommended

All the expert medical organisations and health professionals recommend that you shouldn't drink alcohol in the 1st 12 weeks of your pregnancy.

There's little truly specific research just on alcohol in the 1st trimester; what there is mostly – but not universally – backs these recommendations.

A study of 5,628 pregnant women published in Obstetrics and Gynaecology in 2013¹² found "no association between alcohol consumption before 15 weeks of gestation and [babies being] small for gestational age, reduced birthweight, preeclampsia, or spontaneous preterm birth".

But a study by scientists at the University of Leeds in the same year¹³suggested that the 1st trimester is "the period most sensitive to the effect of alcohol on the developing fetus". And a Danish study published in 2012¹⁴finds that even light drinking in the early weeks can "substantially increase" the risk of miscarriage, indicating that "the fetus is particularly susceptible to alcohol exposure early in pregnancy".

Drinking if you're trying to get pregnant: not recommended

The advice is to avoid alcohol if you're actively trying for a baby. And that's because, if you do conceive, it's highly likely you won't know you're pregnant straightaway (even if you're standing by with an 'early' pregnancy test, you'd have to wait until 4 to 5 days before your period is due). And, by avoiding alcohol while you're trying, you can avoid the possibility of having drunk alcohol when you're pregnant but hadn't found out yet.

It's also worth noting that it's thought drinking alcohol – even lightly – can affect your fertility and therefore reduce your chances of getting pregnant.¹⁵

Heavy (and possibly moderate) drinking throughout your pregnancy: known to be harmful

There's a lot of evidence, acknowledged by the World Health Organisation,¹⁶ that drinking heavily or binge-drinking throughout your pregnancy can lead long-term harm to your baby, including miscarriage and a range of fetal alcohol spectrum disorders, of which fetal alcohol syndrome is the most severe.

There is also some evidence that drinking moderately throughout pregnancy can be harmful, with one study suggesting drinking 3 units, 5 times a month could trigger long-lasting change in your baby's genes and also increase their level of the stress hormone cortisol. ^{17, 18}

Light drinking in your 2nd and 3rd trimesters: no clear evidence of harm

This is the controversial area. Although studies are being done all the time, as yet there is no medical proof that light drinking has any significant impact on your baby during your 2nd and 3rd trimesters.

What the experts say

The Midwife: "Too much alcohol during pregnancy can lead to Foetal Alcohol Syndrome, affecting your baby's growth and mental ability, but this is usually only a problem in persistent heavy drinkers. We follow the Government's guidelines, which is to err on the side of caution and avoid alcohol." Claire Friars, midwife for Tommy's, the baby charity

The Doctor: "We know that heavy drinking definitely causes harm to an unborn baby, but experts are still debating whether low levels of alcohol have any effect.” Dr Dawn Harper, GP and expert on Embarrassing Bodies

The British Medical Association (BMA): Since June 2015, the British Medical Association (BMA) has called for pregnant women, and women who are considering pregnancy, to abstain completely from drinking alcohol throughout pregnancy.

The Royal College of Obstetricians and Gynaecologists (RCOG): Since January 2018, RCOG's position is that "the safest approach is not to drink alcohol at all if you are pregnant or if you think you could become pregnant"

The Royal College of Midwives: Commenting on a 2017 study of the effects of drinking alcohol in pregnancy, Carmel Lloyd Head of Education at the Royal College of Midwives, said: "We would advise any woman who is trying to become pregnant or who thinks she may be in the early stages of pregnancy to refrain from drinking any alcohol. If you need help or support to do this, please do speak to your GP or midwife."

The National Childbirth Trust (NCT): On their website, the NCT states, "Is it safe to drink a little during pregnancy? The advice is: no, not really. Research has shown that even drinking small amounts of alcohol could potentially be harmful for your baby."

British Pregnancy Advisory Service (BPAS): On their website, BPAS says, pretty strongly: "To advise pregnant women, and those who are even thinking of becoming pregnant, to abstain from alcohol completely is a fairly drastic measure. For women who 'do choose to drink' at low or moderate levels, or women who drank before they discovered they were pregnant, the injunction that 'it is better to avoid drinking alcohol completely' instils feelings of guilt and anxiety. The claim that pregnant women cannot tell the difference between sipping small amounts of wine and heavy drinking is fairly insulting to women."

The Academic: "Official advice about drinking in pregnancy has gone down an overtly precautionary route. Evidence that suggests the odd drink, or even more than that, has no impact on child outcomes is interpreted as insufficiently robust and any level of drinking is now associated with harm. [This] creates anxiety and.. the exclusion of women from an ordinary activity on the basis of ‘precaution’ can more properly be called sexist than benign. These are the issues that need to be made the focus for discussion." Ellie Lee, Director of the Centre for Parenting Culture Studies at the University of Kent

How many women drink alcohol during pregnancy?

If MadeForMums users are anything to go by, definitely fewer women are drinking alcohol in pregnancy since the official guidelines changed in 2016.

Back in 2014, we ran a MadeForMums survey, asking more than 1100 women whether they drank during pregnancy. And, according to those results, about a quarter of pregnant women said they stopped drinking alcohol altogether and just under half said they still drank (lightly) while pregnant:

45% said they had drunk alcohol while pregnant
24% said they stopped drinking alcohol when they discovered they were pregnant

But, looking at posts in our MadeForMums Community and talking to the pregnancy women who took part in our Bump Project pregnancy research study, things have changed a lot – with the vast majority of pregnant women saying they avoid drinking in alcohol altogether.

"I personally believe pregnancy should be a no alcohol time," says Emma, for example. And Gemma, who took part in our Bump Project, says, "Before, I loved a glass (or 3!) of red wine but, since becoming pregnant I have not had anything alcoholic. The risks are unknown and I don’t want to take any chances."

What happens when you drink alcohol?

Your baby is nourished through your placenta. Any alcohol that you drink enters your bloodstream as a chemical known as acetaldehyde, and is then passed onto your baby via your placenta.

In her book Expecting Better: Why the conventional pregnancy wisdom is wrong and what you really need to know Emily Oster explains: “Your baby can actually process some alcohol, but not as much as an adult (obviously). If too much acetaldehyde is passed to the baby, it can get into their tissues and impact development.”

How much is a unit of alcohol?

One UK unit is 10ml (or eight grams) of pure alcohol. Look at the label of your drink for the letters ABV, which means Alcohol By Volume. This indicates the strength of the alcohol present.

You will find one unit in of alcohol in:

Half a standard (175ml) glass of wine at 11.5% ABV

Half a pint of beer, lager or cider at 3.5% alcohol by volume (ABV: you can find this on the label)

A single measure (25ml) of spirit, such as whisky, gin, rum or vodka, at 40% ABV

Unsure of how many units there are in a specific drink? Use the drinkaware calculator to find out.

What happens to your baby if you drink too much?

Sustained heavy alcohol use through pregnancy can cause serious, lifelong damage to an unborn baby:

Foetal alcohol syndrome

Children and adults with foetal alcohol syndrome (FAS) suffer a range of problems, from facial abnormalities to behavioural and learning disorders. Visit fasaware.co.uk to find out more.

Foetal alcohol spectrum disorder

Binge drinking (occasional heavy drinking) and drinking more than the recommended levels during pregnancy have also been linked to foetal alcohol spectrum disorder (FASD) – a condition where children suffer some, but not all, of the symptoms of FAS. Visit fasdtrust.co.uk to find out more.

In summary, here's what we know about alcohol in pregnancy:

The official advice is not to drink alcohol at all in pregnancy
Binge drinking (7.5 units or more on 1 occasion) is harmful to your baby
Sustained heavy drinking (7.5 units or more) is harmful
Drinking in your 1st trimester is widely thought to increase the risk of miscarriage
There is little evidence that light drinking (1 to 2 drinks, once or twice a week) in your 2nd and 3rd trimester will damage your unborn baby or affect your pregnancy but most experts advise not drinking, as a precaution.
There's some evidence that moderate drinking (7 units per week) can be harmful to your baby

About the author Helen Brown

Helen is Deputy Editor of MadeForMums, the author of Parenting for Dummies (Wiley, £17.99). She has written about pregnancy and parenting for Mumsnet, Pregnancy & Birth, Prima Baby, Boots Parenting Club and She Magazine and she's also been Consumer Editor of Mother & Baby. She has 3 children and a heavy-duty washing machine.

References:

^{^{1 .Drinking alcohol while pregnant. NHS Online
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4. Evidence of a complex association between dose, pattern and timing of prenatal alcohol exposure and child behaviour problems. O'Leary et al. Addiction, November 2009; DOI: 10.1111/j.1360-0443.2009.02756.
5. Alcohol and pregnancy: Preventing and managing fetal alcohol spectrum disorder. British Medical Association. June 2007 (updated February 2016).
6. Alcohol and pregnancy. RCOG Patient Information Leaflet. Published in February 2015 (revised January 2018)
7. Alcohol and women. ACOG online
8. Evidence of detrimental effects of prenatal alcohol exposure on offspring birthweight and neurodevelopment from a systematic reviews of quasi-experimtental studies. Mamluk L et al. International Journal of Epidemiology. 29 January 2020. doi.org/10.1093/ije/dyz272
9. Low alcohol consumption and pregnancy and childhood outcomes: time to change guidelines indicating apparently 'safe' levels of alcohol during pregnancy? A systematic review and meta-analyses. Mamluk, L. BMJ Open. Volume 7, Issue 7.
10. Advice to pregnant women about drinking alcohol may cause more harm than good. BPAS online.
11. 'Court of Appeal rules that drinking in pregnancy is not a crime' Birthrights online 4 December 2014
12. Association Between Maternal Alcohol Consumption in Early Pregnancy and Pregnancy Outcomes. McCarthy FP. Obstetrics & Gynaecology. October 2013 Volume 122 Issue 4 p 830-837.doi: 10.1097/AOG.0b013e3182a6b226
13. Maternal alcohol intake prior to and during pregnancy and risk of adverse birth outcomes: evidence from a British cohort. Nykjaer, C et al. Journal of Epidemiology & Community Health. Volume 6, Issue 6.
14. Moderate alcohol intake during pregnancy and risk of fetal death. Nybo Anderson, AM et al. International Journal of Epidemiology. Volume 41, Issue 2, April 2012, Pages 405–413, doi.org/10.1093/ije/dyr189
15. Lifestyle factors in people seeking infertility treatment: a review. Anderson, K. Aust N Z J Obstet Gynaecol. 2010 Feb;50(1):8-20. doi: 10.1111/j.1479-828X.2009.01119.x.
16. ‘Fetal alcohol syndrome: dashed hopes, damaged lives’, Bulletin of the World Health Organization 2011, 89, pp. 398–399
17. Persistent Changes in Stress Regulatory Genes in Pregnant Woman or a Child With Prenatal Alcohol Exposure. Sakar DK et al. Alcoholism: Clinical and Experimental Research, 2019; DOI: 10.1111/acer.14148
18. Association of Moderate Alcohol Use and Bings Drinking During Pregnancy with Neonatal Health. Meyer-Lou, Y. Alcoholism Clinical and Experimental Research 35(9):1669-77, May 2011 DOI: 10.1111/j.1530-0277.2011.01514.x}}

What do the latest official UK guidelines say exactly?