Experts provide cold water swimming guidelines during pregnancy

Experts provide cold water swimming guidelines during pregnancy | Image Credit: © nata777_7 - © nata777_7 - stock.adobe.com.

New guidelines for cold water swimming while pregnant

Swimming outdoors in cold water during pregnancy requires informed, expert-led opinions, according to a recent study published in Lifestyle Medicine.¹

The new guidelines recommend pregnant patients only swim in cold water if they are regular cold water swimmers, do not swim alone, and avoid cold water swimming if they have raised or very low blood pressure. Further research is necessary to expand on these recommendations.¹

“Getting pregnant can lead to a mum-to-be to stop or start certain pastimes to support her health and the baby’s development,” said Jill Shawe, DO, FACOG, professor at the University of Plymouth.¹ “However, there’s so little out there about cold water swimming in pregnancy that women are left in the dark when it comes to making a decision on whether to continue swimming or not.”

Study methodology and expert consultation

Investigators conducted a study to form evidence-based guidelines about the safety of cold water swimming during pregnancy.² Recommendations were obtained through virtual meetings of experts including exercise physiologists, cold water physiologists, and fertility, obstetrics, neonatology and midwifery, public health, and water epidemiology specialists.

During the meetings, experts discussed key questions to improve knowledge and evidence surrounding cold water swimming during pregnancy. Following the meetings, gatekeepers of closed social media groups were contacted for permission to ask members about questions related to cold water swimming.²

Questions were related to temperature, physiological fetal responses, water quality, trimester, wetsuits, health conditions, experience of cold water, birth outcomes, postnatal, swimming stroke, sea conditions, temperature post-swim, in vitro fertilization, mental health, specific pregnancy considerations, outdoor vs indoor, and adipose fat changes.²

Physiology and temperature, water quality, and pregnancy-specific risks were the most common concerns among women. Articles about these topics were obtained through literary searches of medical databases conducted by 2 reviewers.²

Six studies met the inclusion criteria for cold water swimming and pregnancy and were included in the analysis. There was little research available, and the current data focused on physiological response to cold water and pregnancy, alongside water quality. The questions obtained from social media groups were associated with available data.²

Research findings and physiological effects

While information about the effects of cold shock on pregnant women was not available, data indicated a more significant reduction in pedal oedema from 20 minutes of standing water immersion at 28 to 29 degrees Celsius vs seated rest on land with legs elevated. Immersion in water was also linked to reduced odds of restless leg syndrome.²

Cortisol concentrations did not rise in pregnant women using a 1 minute cold pressor test, vs significant elevations in matched non-pregnant controls. Pregnant groups at rest reported similar increases, indicating hand immersion does not lead to an increase in cortisol among pregnant patients.²

Four cases of hypothermia during pregnancy were reported. All but 1 of these cases led to the delivery of a healthy delivery, and the single case of spontaneous preterm birth was liked to multiple potential sources.²

Two cases of accidental hypothermia were also reported, both resulting in a healthy infant. However, follow-up data was not available. While this indicated no direct harm to the fetus from hypothermia, investigators noted a link between maternal temperature and fetal heart rate.²

When evaluating water quality, investigators highlighted concerns of gastrointestinal illnesses, including more severe infection from micro-organisms such as E. coli O157. However, 1 study found no link between gastroenteritis during pregnancy and neonatal outcomes except for a slight decrease in pregnancy duration and an increase in preterm birth risk.²

Conclusion

Risks of adverse outcomes may be increased from submerging in open water locations not designated as bathing waters. Blue-green algae in freshwater has been indicated as the highest risk, though the risk of harm may not be clear from appearance alone. Therefore, investigators recommended selecting locations where water quality is carefully measured.²

“Now, with this new study in pregnant women as a launchpad, we have meetings planned to look at next steps, including prioritizing studies working with pregnant women to ascertain their experiences, and directly measuring the impact of cold water swimming on the fetus too,” said Shawe.¹

References

1. Is it safe to swim outdoors during pregnancy? New study opening doors to find out. University of Plymouth. February 24, 2025. Accessed March 4, 2025. https://www.eurekalert.org/news-releases/1074668
2. Shawe J, Felton M, Harper JC, et al. Cold water swimming and pregnancy: A scoping review and consensus recommendations. Lifestyle Medicine. 2025. doi:10.1002/lim2.70009