Dr Malika Felton, on behalf of the SwimHer Research Network
Senior Lecturer in Health and Exercise Physiology, Bournemouth University
For anyone living or visiting the coast or an open body of water over the past few years, I am sure you have noticed the recent increase in people swimming or taking a dip, not just in summer but throughout the year. Many people swim as part of locally organised groups, such as The Bluetits Chill Swimmers which has grown from 5 groups in 2020 to around 200 groups worldwide in just a few years, with over 100,000 members. There are a large range of perceived benefits for mental and physical health and specifically for women related to menstrual and perimenopause symptoms.
The increase in numbers of people, and specifically women, taking part in cold-water swimming, means that many women who are currently taking part in cold water swimming are getting pregnant and wondering whether they can continue to take part in the activity that they love. Is it safe to continue cold water swimming and are there extra factors that need to be considered?
“Once people have experienced the benefits of cold water they generally don’t want to stop”
Gail Bainbridge, The Bluetits Chill Swimmers
Carmel Lawless, who lives in Plymouth, enjoyed cold water swimming, and planned to continue the pastime when she became pregnant in 2022.
“There are so many physical and mental health benefits to sea swimming that I didn’t want to stop but I felt guilty and irresponsible every time I entered the water. It was reassuring yet frustrating that I – along with others seeking to swim outdoors during pregnancy – were all being told to abstain not necessarily because it was too dangerous but because there wasn’t enough evidence of what the risks might be.”
Carmel and other pregnant women shared their experiences as part of Immersion Maternal, a study which explored the reasons why people choose to swim outdoors during pregnancy and formed part of the Planet Ocean exhibition at the Box Plymouth. The universal message received from all women was that they wanted more research in this area so they could make informed decisions and have open conversations with their healthcare professional, to minimise any potential risk to themselves and their children.
The SwimHer Research Network are taking on this challenge and have collated a list of questions from these women, and others asked on social media. The first step was to find out what existing evidence and guidance is available specifically for cold water swimming during pregnancy, to try to answer the questions that women had asked.
Unfortunately, but perhaps not surprising for anyone that has been pregnant or works in the maternal field, limited information was found. Only six research articles and eight reports were found and no study had taken place in a large enough group to offer significant insight, with the studies highlighting large gaps in knowledge.
As part of this work, the SwimHer Research Network produced recommendations for pregnant women, but because of the limited existing information available, the advice was mainly based on informed, consensus-led expert opinions. The recommendations include advice to:
Only swim in cold water during pregnancy if a person is a regular cold water swimmer before pregnancy;
Complete the Get Active Questionnaire for Pregnancy (GAQ-P) before undertaking any physical activity during pregnancy, including cold water swimming;
Not swim alone;
Consider wearing gloves and a hat to minimise heat loss, especially when a wetsuit or skins may not longer fit due to pregnancy;
Avoid bathing on higher risk days which follow heavy rainfall (1-2 days) and in water with blue-green algal blooms or scums;
Avoid cold water swimming altogether if blood pressure is raised or very low and check with your healthcare professional for other health conditions.
The full recommendations can be read in the journal Lifestyle Medicine, which is available to all free of charge (top tip - to skip the academic content, head straight to Table 1 (page 4) to see the full list of questions that women asked, and to Table 3 (page 8 and 9) to read the recommendations).
This work outlines the future research that needs to be taken in the area, and the SwimHer Research Network have just met up in Cornwall to discuss the next steps for the research in pregnancy and through perimenopause. The photo below shows the group joined by members of the Cornish Kelpie Sea Swim Adventure group, who took us out for a swim in Carbis Bay, Cornwall. I will admit to sitting this one out, and being tasked with photographer for the day, which meant I got to enjoy seeing the seal from the shore!
Calls to action
The first call to action is to please share these recommendations with anyone working in the maternal field so they can provide advice to pregnant women, and also share with anyone you know making the decision whether to continue cold water swimming while pregnant.
Secondly, the majority of the current advice is based on expert opinion and applying knowledge from other areas of pregnancy or general cold water swimming advice. Future research needs to provide evidence to support evidence-based guidelines. The research priorities based on the questions provided by women are as follows (in no particular order):
What are the immediate physiological responses to cold water immersion, such as maternal heart rate and blood pressure, and fetal heart rate?
Are there longer term health impacts of cold water immersion on the health of mother and baby, including pregnancy and birth outcomes?
Do the physiological responses to cold water immersion change across different trimesters?
Is there an optimum dose of cold (temperature and duration) during pregnancy?
Does cold water immersion impact the success of IVF treatment?
If experiencing morning sickness should cold water immersion be undertaken? Can cold water immersion change the symptoms of morning sickness (reduce or make them worse)?
Does pregnancy increase the risk of adverse events, such as arrhythmias, SIPE, and global transient amnesia?
Are pregnant women at greater risk from poor quality bathing water?
Does cold water immersion benefit mental health in pregnancy or have an impact on postnatal depression?
Does cold water immersion have the potential to reduce inflammatory responses? Can inflammatory-related conditions in pregnancy be managed by cold water immersion?
“With this new study in pregnant women as a launchpad, the SwimHer Research Network are planning the next steps, including prioritising studies working with pregnant women to ascertain their experiences, and directly measuring the impact of cold water swimming on the foetus too.”
Jill Shawe, Professor of Maternal and Family Healthcare, University of Plymouth
Acknowledgements
This article was written on behalf of the SwimHer Research Network. We were set up to bring together people researching in the area of cold water swimming related specifically to women throughout different stages of the life, including the impact during menstruation, while trying to conceive, during pregnancy and through perimenopause and beyond. We are a truly interdisciplinary team containing people with backgrounds from cold water and exercise physiologists to specialists in fertility, obstetrics, neonatology, midwifery, water epidemiology and public health.
If you are interested in getting involved please do get in touch (mfelton@bournemouth.ac.uk).
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