It is best to avoid a hot tub or sauna in the first 12 weeks of pregnancy, as use has been associated with miscarriage and neural tube defects. After the first trimester, it may be reasonable to spend short periods of time (10 minutes) in a hot tub or sauna. In general, it is important to stay hydrated and avoid getting overheated in pregnancy. Avoid hot tubs and saunas if you have chronic health conditions or pregnancy complications such as high blood pressure or issues with the baby’s growth.
The risk of hot tubs and saunas is related to the increase in core body temperature. In the first trimester, a body temperature over 101 F or 38.3 C has been associated with birth defects and pregnancy loss. Fever as a result of illness is another way the developing embryo or fetus is exposed to high temperatures. Consult with your Ob provider should you experience a fever (T 100.4 F/38 C or above) particularly if it is in your first trimester.
It is safe to take baths at home, provided you use water less that 101 F, unless you are told otherwise by your Ob provider.