For a pregnant woman who wants to relax, the world can seem full of potential dangers. Hot tubs are often forbidden to pregnant women, as many fear that a soak in a hot tub will cause spinal bifida. While there are certainly things that should be avoided entirely during pregnancy, hot tubs don’t necessarily deserve to be on that list. In reality, the potential for hot tubs to cause spinal bifida is often greatly overstated. Although a small window of potential concern might exist, pregnant women generally shouldn’t fear hot tubs.
The studies that started the myth
The fear that hot tubs cause spinal bifida can be traced back to a frequently cited and often misunderstood animal studies from the 1970’s and 80’s. These studies exposed animal models, from rats to baboons to 104 – 106 degree F. temperatures for an extended period of time. The findings suggested increased likelihood of spinal tube defects in animals, but this information would only be remotely applicable to humans. Also, It takes over one hour of complete immersion in a hot tub to raise your core body temperature anywhere near the danger zone.
Spinal development in humans
While the heat did increase defects of the spinal tube in a developing animal fetuses, that doesn’t guarantee the risk is the same for humans. In human pregnancy, the spinal tube forms as a flat plate of neural tissue that then curves up into a tube-like structure and seals closed from the center to both ends. A neural tube defect is a failure of the top or bottom of this tube to close, leading to either anencephaly or spinal bifida, respectively.
By 6 weeks of gestation, the neural tube is completely and permanently closed. After that point, spinal bifida is no longer possible to develop. This means the window of opportunity for spinal bifida to form is relatively small. Many moms-to-be don’t even realize they’re pregnant until the first 6 weeks (28 days after conception) are over.
Actual risks are likely minimal
In addition to the small biological window of potential risk, the danger of hot tubs causing spinal bifida is further diminished by hot tub regulations and advisories. Most hot tubs sold in the United States are limited to 104 degrees Fahrenheit. These hot tubs can never match the higher heat used by the study. Also, even non-pregnant adults are advised to only stay in hot tubs for around 15 minutes at a time, far below the study’s exposure times of an hour or more. While many adults choose to stay in a hot tub for longer than the recommended period of time, moms- to-be would be far less likely to voluntarily sit in a hot tub for very long. Pregnancy tends to make women heat-intolerant, so any discomfort would be noticeable relatively quickly.
If you’re concerned about any risk, no matter how theoretical or small, then simply avoid hot tubs until the first 6 weeks of pregnancy have passed. If you want to enjoy the relaxing effects of a hot tub later in your pregnancy, you can always turn the temperature down to 100 degrees and take frequent breaks, especially if you start to feel discomfort or lightheadedness.
While there is a small window of potential concern, it’s unnecessary to spend the rest of your pregnancy avoiding hot tubs if they make you comfortable and provide relief from aches and pains. Enjoy yourself, but be aware of the temperature and remember to get out if you start feeling unwell.
Always speak with your doctor if you have any questions or concerns. No pregnancy is perfect, but I hope your pregnancy is the very best it can be.
Be safe, be well and have fun!
David L. Berry, M.D.
Founder and Staff Physician
Austin Perinatal Associates