18 November 2020
We’re calling for expectant parents to have more support and guidance on caffeine intake during pregnancy, as the latest study from our Maternal and Fetal Health Research Centre shows that 1 in 20 women increased their caffeine consumption while pregnant despite evidence that some caffeinated drinks can endanger babies’ lives. The overall risk is small, but our stillbirth research experts are concerned that many people are unaware of - or confused by - this risk.
What our scientists found
Our research clinic team studied more than 1,000 mothers across 41 UK hospitals between 2014 and 2016, combining information typically used to measure stillbirth risk with an interviewer-led questionnaire about mothers’ consumption of various caffeinated drinks (as well as other risk factors like alcohol and cigarettes that have muddied the waters in previous studies) to see if and when stillbirth may have been linked to caffeine.
Current NHS guidance is to keep daily caffeine intake below 200mg when pregnant, while the World Health Organization (WHO) cites 300mg as the safe limit. This new study reports a 27% increase in stillbirth risk for each 100mg consumed, suggesting that safe limits in these guidelines need to be reconsidered. Although most (54.5%) people cut down on caffeine while pregnant, 1 in 20 actually increased their intake, showing a lack of awareness about caffeine consumption and the risks.
The main source of pregnant women’s caffeine consumption was tea, but this wasn’t found to pose a significant risk due to its low caffeine levels. Filtered or decaffeinated coffee, chai, green tea and hot chocolate were also shown to have no association with stillbirth. Energy drinks had the most impact, leading to 1.85x higher stillbirth risk, followed by instant coffee (1.34x) and cola (1.23x). It wasn’t possible to separate the impact of caffeine from that of sugar in cola and chemicals like taurine in energy drinks, so we need to investigate this further.
Why this research matters
In the UK, 1 in every 250 pregnancies ends in stillbirth (when a baby dies after 24 weeks gestation). Research has identified various things that can raise stillbirth risk, from a mother’s age and ethnicity to consumption of cigarettes and alcohol, but this study aimed to clarify the mixed evidence on caffeine – a key issue in a country where 80% of the population drinks coffee and the average person consumes 211.5 litres of (often highly caffeinated) soft drinks a year.
Caffeine, like many substances found in a normal diet, can be harmful in large amounts; babies can’t process it like adults, so when it crosses the placenta it can endanger their lives. Even though a little bit can be okay, staying on the safe side can help mums to have a healthier pregnancy and the official guidance is to keep caffeine consumption low while pregnant. However, measuring caffeine isn't always easy, and our PregnancyHub team regularly encounters confusion and concern among mums-to-be.
Stillbirth causes often have nothing to do with diet and lifestyle, but we know there are some things we can do to reduce the risk of this tragedy, which is why these latest research findings need to be shared as widely as possible. A poll we ran found 61% of mums would consume less caffeine after finding out how much is ‘hidden’ in certain soft drinks, so raising this awareness is a vital part of our mission to save babies’ lives.
Where to go from here
The stillbirth experts behind this new research have called for its findings to be shared with parents and professionals alike, as the study found that midwives were the biggest influence on pregnant women’s caffeine consumption – but other research shows that caffeine isn’t often mentioned at antenatal appointments. It’s very hard to put these complex risks into simple terms, so healthcare professionals may also need specialist guidance to help them do this.
Study author Prof Alexander Heazell, Tommy's research centre director and professor of obstetrics at the University of Manchester, explained: “Anyone planning to have a baby needs to know that consuming caffeine during pregnancy can raise the risk of stillbirth and other pregnancy complications, so it’s important to cut down as much as you can; the national guidelines should be the limit, not the goal, and the more you can cut down beyond that the better. Breaking habits can be hard, but little things like switching to decaf and swapping fizzy drinks for fruit juice or squash can really help reduce the risk.”
Charlotte Stirling-Reed, registered nutritionist and mum to three-year-old Raffy and four-month-old Ada, said: “Caffeine intake can be really confusing. Even as someone with a background in nutrition, it can be hard to work out the amounts in different drinks and how much is consumed each day. Often many people just aren’t aware of how much caffeine there is in some of their favourite foods and drinks.
“All mums want the best for their baby, during pregnancy and beyond, and so anything that can be done to help break down the guidance and give practical tips on why and how to cut down is really important. We don’t want to make anyone more worried during pregnancy, so it’s really key to get credible and supportive messages out, and Tommy’s is doing wonderful work at offering practical tools without scaremongering.”
Tommy’s chief executive Jane Brewin commented: “Eight babies are stillborn every day in the UK, and the reasons often have nothing to do with diet and lifestyle – but we know there are some things we can do to reduce the risk of this tragedy, so communicating these latest research findings as widely as possible is a vital part of our mission to save babies’ lives.”
Caffeine is just one aspect of pregnancy health, alongside vital things like eating a balanced diet, keeping physically active, going to antenatal care appointments and seeking help for unusual symptoms. Find out more about how to improve pregnancy health with our new tool - and anyone unsure how much caffeine they consume can use our calculator, which also gives advice on ways to cut down that will have an immediate positive impact.
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