Energy drinks can raise stillbirth risk and caffeine guidance confuses mums-to-be, new research warns
Stillbirth experts warn that expectant parents need to know more about caffeine, as a new study from Tommy’s Maternal and Fetal Health Research Centre at the University of Manchester shows 1 in 20 women increased their intake during pregnancy, despite evidence that some caffeinated drinks can endanger babies’ lives*.
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 the risk of stillbirth, 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***.
Scientists from Tommy’s stillbirth research centre at the University of Manchester studied more than 1,000 mothers across 41 UK hospitals between 2014 and 2016. They combined 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 confused previous studies, to see if and when stillbirth may have been linked to caffeine****.
When caffeine crosses the placenta, babies can’t process it like adults, and it can endanger their lives. 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.
The Tommy’s team found an increasing relationship between caffeine consumption and stillbirth risk – and although most (54.5%) participants cut down on caffeine while pregnant, 1 in 20 actually consumed more during pregnancy, showing a lack of awareness about the caffeine content of certain drinks and/or the risks associated with high intake.
Energy drinks had the most impact, leading to 1.85x higher stillbirth risk, followed by instant coffee (1.34x) and cola (1.23x). Researchers noted that it wasn’t possible to separate the impact of caffeine from that of sugar in cola and chemicals like taurine in energy drinks, so more detailed investigation is needed.
The main source of pregnant women’s caffeine consumption was tea, but the study found this did not pose a significant risk as its caffeine levels are quite low (around 75mg per 350ml). Filtered or decaffeinated coffee, chai, green tea and hot chocolate were also shown to have no association with stillbirth.
Study author Prof Alexander Heazell, Tommy's research centre director and professor of obstetrics at the University of Manchester, commented: “Caffeine has been in our diets for a long time, and, as with many things we like to eat and drink, large amounts can be harmful – especially during pregnancy. It’s a relatively small risk, so people shouldn’t be worried about the occasional cup of coffee, but it’s a risk this research suggests many aren’t aware of.
“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. If you’re worried or confused, talk to your doctor or midwife, or use tools like Tommy’s caffeine calculator.”
Caffeine has been in our diets for a long time, and, as with many things we like to eat and drink, large amounts can be harmful – especially during pregnancy. It’s a relatively small risk, so people shouldn’t be worried about the occasional cup of coffee, but it’s a risk this research suggests many aren’t aware of
A 2018 poll by Tommy's found that 61% of women would consume less caffeine after being made aware of how much is ‘hidden’ in certain soft drinks*****, and the charity has free online resources to help mums-to-be understand and reduce their pregnancy risks, including a caffeine calculator and healthy pregnancy tool.
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 consumed, and many people just aren’t aware of how much caffeine is in some of their favourite foods and drinks.
“All mums want the best for their baby during pregnancy and beyond, 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. Tommy’s research and practical tools are really key to supporting as many families as possible.”
The UK’s stillbirth rate is 24th out of 49 high-income countries******, and while a Government aim to halve stillbirth rates by 2025 has resulted in promising initiatives like the NHS Saving Babies’ Lives Care Bundle, campaigners are calling for more concerted efforts to educate parents and professionals about the risks.
Tommy’s chief executive Jane Brewin explained: “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.
“This study found that midwives and internet resources had the most impact on pregnant women’s caffeine consumption, so we need to make better use of their influence to support mothers throughout their pregnancy journey. Risk is a complex concept to communicate, so healthcare professionals may need training to help them get these messages across.”
The new study was published today in the European Journal of Obstetrics and Gynaecology. To find out more about Tommy’s stillbirth prevention work, go to tommys.org/research. For information and advice on pregnancy health, visit tommys.org/your-pregnancy-1-2-3, or you can measure your caffeine intake at tommys.org/caffeine-calculator.
**** The Midlands and North of England Stillbirth Study (MiNESS) was a case control study of 1,024 pregnancies across 41 UK maternity units from 2014-16, comparing 291 non-anomalous singleton stillbirths at/before 28 weeks gestation with no congenital anomaly to 733 ongoing pregnancies. Researchers combined information on factors associated with stillbirth and typically used to measure risk with responses to an interviewer-administered questionnaire on maternal behaviours, including consumption of a variety of caffeinated drinks and soft drinks (instant coffee, filter coffee, decaf coffee, tea, chai, green tea, hot chocolate, energy drinks, cola). Anecdotally, older women often drink more caffeine, and those who drink more caffeine are more likely to smoke and drink alcohol; these factors are also associated with stillbirth and existing research evidence has been unable to separate the risks. This study used multivariable analysis to adjust for co-existing demographic and behavioural factors (age, ethnicity, BMI, smoking, alcohol, education, supplements, sleep habits, gestation and weight at birth) to determine if/when stillbirth was linked to caffeine.