Is It Safe to Sit In a Hot Tub When Pregnant?

The Riskiest Time During Pregnancy

• During the first three months of pregnancy, your baby's organs and basic structures are forming, so this particular time presents the greatest risk for birth defects to develop. Raising your internal temperature to 101 degrees Fahrenheit or higher can pose a risk for birth defects. The American College of Obstetricians and Gynecologists cautions that pregnant women should never allow their core temperature to exceed 102.2 degrees; hot tubs are normally heated to 104 degrees. Spending just 10 to 20 minutes in the tub can raise your temperature to the danger level, the American Pregnancy Association warns. Limit your time to less than 10 minutes, or better yet, stay out altogether.

Birth Defects and Hot Tubs

• A University of Texas study published in the September 2011 issue of "Birth Defects Research" shows that pregnant women who spend time in hot tubs during the first trimester of pregnancy have a higher risk of giving birth to a baby with neural tube defects such as anencephaly, which is the absence of part of the brain. Hot tub users also have a higher risk of having a baby with several types of abdominal birth defects, such as gastroschisis, where the internal organs protrude outside the abdominal cavity. The study also found increases in esophageal atresia and omphalocele, two other types of gastrointestinal defects, in women who used the hot tub several times for more than 30 minutes during early pregnancy.

Miscarriage and Hot Tub Use

• Hot tubbers might also have a higher risk of miscarriage in the first trimester, found a review of studies conducted by the Kaiser Foundation Research Institute and published in the November 2003 issue of the "American Journal of Epidemiology." Hot tub use doubled the risk of miscarriage; the rate of miscarriage also increased further with heavier hot tub use. The risk was also higher in women who used a hot tub in the first four weeks after their last menstrual period, before they had a missed a period or realized that they were pregnant.

Infection Risks

• Because your immune system is depressed during pregnancy, you are actually more vulnerable to infection. Hot tubs encourage the growth of bacteria, such as Pseudomonas aeruginosa, which thrive because of the water temperature and the aeration. Pseudomonas aeruginosa can cause respiratory and skin infections, as well as urinary tract infections, which can cause preterm labor in later pregnancy, according to a study published in the 2009 "Reviews of Environmental Contamination and Toxicology."