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Friday 27 December 2019

Alcohol and Caffeine (Things We Don’t Know about Pregnancy Series #9)

It’s the Christmas season and, for many people, time to get merry. But pregnant women can’t drink – alcohol or caffeine – or can they?

All things, wrote Paracelsus, are poison and nothing is without poison, only the dose permits something not to be poisonous.

And dose, apparently, works both ways. You may be able to have too much of a good thing, but you may also be able to have too little of a bad thing.

We often think that a drug does nothing to us until the point where it has an effect – the threshold dose. However, this describes a linear dose-response relationship… which doesn’t fit every drug. Researchers think that some substances follow a biphasic dose response: at some point they switch over from stimulating to inhibiting or from inhibiting to stimulating. Alcohol is one such drug.

This dose response phenomenon is known as hormesis, and is explained in more detail in this article.
The hormetic effect. © TWDK.


This means that a small amount of alcohol could have the opposite effect to a large amount – and may even be good for you (although, importantly, hormesis describes stimulation and inhibition, not necessarily “good effect”/”bad effect”). Small amounts may prevent heart disease and stroke, and lengthen life span[1][2]. The biochemical mechanisms behind hormesis are not well understood.

However, in contrast to this evidence, medical advice remains that no alcohol is safe during pregnancy. Doctors and midwives don’t trust women to make decisions, and are worried that putting a numerical limit on alcohol will encourage women to push the limit (so essentially treat women like children). To me, this is simply another example of how society and the medical profession assume control over women’s bodies, especially if you’re pregnant. We may have abortion rights in this country, but if you’re keeping your baby, you’re no longer autonomous.

And this extends beyond pregnancy: women trying for a baby are advised not to drink at all (as are men). Studies have shown conflicting results, and are complicated by confounding lifestyle factors. Further, most studies are carried out on very small cohorts (or cohorts that become small once categorised to adjust for other factors), and results are not always statistically significant. One (non-specialist) doctor put it to me in plain language I can understand: “There is no evidence that alcohol or stress can stop a sperm from meeting an egg.” However, there does appear to be some evidence that drinking alcohol and caffeine increase the probability of early spontaneous abortion or lower the chance of conception; however, results are uncertain and more work is [3][4][5]

Many women sadly terminate a pregnancy because they believe they have harmed the baby through drinking irresponsibly before they found out. This is entirely due to bad advice and lack of information allowed to women, because if conception is successful and miscarriage doesn’t take place, drinking this early (before the development of the nervous system) can’t cause foetal alcohol syndrome, the risk for which peaks at 6-9 weeks of pregnancy (of course, it’s entirely possible to not know you’re pregnant during these weeks – my mum didn’t realise until she was 12 or 13 weeks! But this would mean missing one or two periods and not suspecting).


How does alcohol harm your unborn baby?

We still don’t know a lot about alcohol or its harmful effects – including why it causes hangovers. However, research suggests it has multiple effects on the developing foetus, including[6][7]:

Alcohol consumed with food slows down its metabolism. © TWDK.
• inhibiting the development of the nervous system
• altering foetal DNA or gene expression
• effecting heart rate and cortisol levels
• producing reactive oxygen species, which accelerate cell ageing and death
• upsetting glucose, protein, lipid and DNA metabolism

These effects may come from alcohol metabolites rather than or as well as the alcohol itself, which is why it’s important to drink slowly and ensure your body doesn’t build up these toxins.

So what ARE the numbers?

Emily Ostler’s comprehensive literature review suggests that there is no proven harm to your unborn baby if you consume 1-2 alcoholic drinks a week in the first trimester, up to 1 drink a day in the second and third trimester, and consume them slowly, with food[8].



Cup of tea. Image via Wikipedia Commons.
During the critical first trimester, most women get sick and go off bitter things, including coffee. This has completely messed up medical research into the effects of caffeine, because it’s difficult to untangle high consumption from lack of sickness (women who feel sick have a higher probability of a healthy pregnancy, and lower probability of spontaneous abortion). Some research suggests caffeine magnifies other negative effects (such as drinking too much alcohol) [5]. Effects are only seen amongst those drinking more than 4 cups of coffee a day, and up to 2 cups has been considered definitively safe[8].

During the first trimester of my pregnancy, I went off – of all things – water. Caffeinated beverages and alcohol were even more repulsive to me, so obviously I never faced this conundrum. More lately, I have been mostly drinking decaffeinated beverages, but not exclusively, and have had some alcohol with food, mostly wine, and certainly less than 1 drink per day. I’ve also been exploring non-alcoholic beers, alternative soft drinks, and even have an interesting bottle of 0.3% martini in the kitchen (serve with ice, in a fancy glass with an umbrella)!

Herbal teas

Many women turn to herbal teas as an alternative to caffeinated beverages, but be careful to do your research if you choose this path: not all herbal teas are safe for pregnant women. Sure, they’re natural and come from plants, but this tells us less than nothing about safety (just think: tobacco comes from a plant and nicotine is a deadly nerve toxin definitely not safe during pregnancy).

Some herbal teas still contain caffeine, and some, such as green tea, contain a lot. Herbal remedies tend to be unregulated, and natural concentrations of components can vary wildly, making amounts on packets rough guidelines at best. It also depends how you’re taking some compounds, such as aloe vera, which is safe to use on the skin, but not to ingest.

One recommended, safe tea is peppermint tea (which can even ease nausea, whilst chamomile is not a good idea (it can trigger uterine contractions). Nettle tea, meanwhile, is sometimes recommended, and sometimes recommended against – more research is needed into its effects.

Confounding factors and environmental exposures

There are lots of other things pregnant women are advised to avoid, including mobile phones, fire retardants, non-stick coatings, and endocrine disrupting chemicals such as bisphenol A and phthalates, found in many plastics and personal care products.

Pharmacy Personal care products, including those marketed at pregnant women, may be best avoided during pregnancy. Image via Wikipedia Commons.

Whilst eating fresh rather than processed foods, minimising painting and use of cosmetics (or fancy pregnancy oils, creams and other unnecessary personal care products) are sensible moves, the exposure levels to these things are so low that they’re pretty much negligible anyway. However, these things do create confounding factors that make assessing the impact of particular foods, drinks or chemicals difficult if not impossible to quantify.

For more about chemical environmental exposure during pregnancy, read our blog post on the topic

There are many unknowns when it comes to pregnancy, and over the next few months, I’ll be exploring more of them with you. Look out for my next blog post, which will be about thalidomide.

You can also read our full article on the things we don't know about pregnancy. This article will be updated as we add posts across the coming months.

why don't all references have links?

[1] Standridge, John B., Robert G. Zylstra, and Stephen M. Adams. Alcohol consumption: an overview of benefits and risks. Southern Medical Journal 97.7 (2004): 664-673.
[2] Schmidt, W., Robert E. Popham, and Y. Israel. Dose‐specific effects of alcohol on the lifespan of mice and the possible relevance to man. British journal of addiction 82.7 (1987): 775-788.
[3] Henriksen, Tine Brink, et al. Alcohol consumption at the time of conception and spontaneous abortion. American Journal of Epidemiology 160.7 (2004): 661-667.
[4] Passaro, Kristi Tolo, et al. Effect of paternal alcohol consumption before conception on infant birth weight. Teratology 57.6 (1998): 294-301.
[5] Hakim, Rosemarie B., Ronald H. Gray, and Howard Zacur. Alcohol and caffeine consumption and decreased fertility. Fertility and sterility 70.4 (1998): 632-637.
[6] Ornoy, Asher, and Zivanit Ergaz. Alcohol abuse in pregnant women: effects on the fetus and newborn, mode of action and maternal treatment. International journal of environmental research and public health 7.2 (2010): 364-379.
[7] Goodlett, Charles R., and Kristin H. Horn. Mechanisms of alcohol-induced damage to the developing nervous system. Alcohol research and health 25.3 (2001): 175-184.
[8] Emily Ostler, Expecting Better: Why the Conventional Pregnancy Wisdom is Wrong - and What You Really Need to Know (2013) Penguin Press.

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