Why Are Hot Tubs Unsafe During Pregnancy?

pregnant hot tub

Pregnancy is often a time of “NOs”: no sushi, no manicures, and no caffeine. This made me think about another of my favorite relaxing activities that I’ll probably have to give up once pregnant--taking a nice long soak in a hot tub. Carrying a baby brings about nausea, muscle aches, and swelling that can often be eased by the soothing effects of hot water. We all know that pregnant women are recommended to stay away from whirlpools and spas during their nine month gestation, but have you ever wondered why? That led me to examine this question: Why are hot tubs unsafe during pregnancy?

Surprisingly, the chemicals in a spa aren’t a factor in this recommendation as long as the pH levels of the hot tub are balanced properly. In actuality, the biggest issue with getting in a hot tub while pregnant is hyperthermia, the raising of the body’s normal temperature to unsafe levels. Since most hot tubs are factory programmed to keep the water at 104 degrees, it only takes 10-20 minutes to raise the body’s temperature to 102 degrees or higher. The Organization of Teratology Information Services (OTIS) points out that a body temperature of 101 degrees and above can lead to problems with a woman’s pregnancy. The American College of Obstetricians and Gynocologists (ACOG) recommendations are a bit more lenient, suggesting pregnant women not let their core body temp climb higher than 102.2 degrees Fahrenheit. Research  has shown that high heat from fever, hot bath, or hot tub can cause birth defects.


The highest risks during a pregnancy arise during the first trimester of a woman’s pregnancy; this is the point that women and their babies are most susceptible to birth defects and even miscarriage if they’re not careful about their water temperature. It’s at this time that women should be most mindful about subjecting themselves to the effects of hot water.

Women are often warned to stay away from hot tubs because they double the risk of neural tube defects. Already one of the most common birth defects, a NTD is caused when a specialized group of cells begin to change shape and form the neural tube. When that tube doesn’t close completely, this results in an NTD.

From the Docs

Jeanne-Marie Guise, OB-GYN

“[It’s] not a good idea unless you can control the temperature and set it at no more than 100 degrees Fahrenheit. Soaking in hot water or sitting in a hot, steamy room can make you overheat, which raises your heart rate and reduces blood flow to your uterus, potentially putting your baby under stress or interfering with normal development. And because pregnant women have a hard time cooling down, you’re more likely to pass out if you get overheated in a hot tub or sauna.”

Catherine Lynch, OB-GYN

“We know that water over 105 degrees is damaging to developing cells. It won’t damage yours, but the baby is sitting in fluid that is also going to get very warm. And extreme temperatures can damage early embryos. So hot-tubbing in the first trimester could cause malformations in the fetus or cause you to lose the baby.”

Safer Alternatives

For those of you like me who can’t help but love steaming hot water, you can still take baths, which are a much safer way to relax. Much of your upper body will stay out of the water and help you maintain a regular body temperature. When your whole body is submerged in hot water like it is in a spa, your likelihood of overheating skyrockets. Keeping your chest out of water helps you regulate your body temperature much more effectively.

If you do decide to soak in a hot tub of your own, here are some pointers to help you avoid some of the potential risks:

  • Avoid getting in hot tubs during that first trimester of pregnancy when you’re the most susceptible

  • Re-program your hot tub to a lower temperature, preferably at 100 degrees or under if you plan on using it frequently

  • Limit your soaking time to ten minutes or less

  • Listen to your body—get out of the water immediately if you have stopped sweating or you feel uncomfortable; these are often indicators that your body temperature has risen to an unsafe level

I hope this has answered some of your questions about hot tubs and pregnancy--I know it did mine! Were you careful about hot water while pregnant?
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