One Hot Mama! Hot Tubs In Pregnancy

by Dr. Michele Brown OB/GYN

pregnant woman lounging in hot tubThe warm fragrant waters of elegant spas around the world are often filled with fully submerged, happy, pregnant women. Why? Because pregnant women can be plagued with multiple body aches and discomforts caused by rapid expansion of the abdomen. This is especially true in the third trimester when we OBs hear many complaints of pelvic discomfort and severe lower back pain.

Our recommendations vary from massage, maternity supports, chiropractor visits, and the like but a warm bath, shower, jacuzzi or hot tub is often the most accessible modality for relief a patient's aching joints and muscles. A woman can go home and kick back with a good book in her own bathtub, or get her husband to spring for a weekend at a luxurious spa. Ahhhhh, what a relief!

Is Heat Safe for the Developing Fetus?

Is this yet another simple pleasure which may not be safe for our unborn babies? Allow me to share the latest research so you and your doctor can make the right choices.

Intense heat has been found to cause fetal malformations in many animal species like chickens, mice, guinea pigs, monkeys and pigs. Past older literature also attributes high maternal temperatures with multiple congenital anomalies in humans, especially when exposure occurs in the first trimester. Risks of neural tube defects is estimated to be about two to four times higher when a first trimester mom's body overheats, either from an external source, such as a hot tub or sauna, or from an internal source such as a fever.

Among the anomalies described are:

  • Neural tube defects
  • Anencephaly
  • Microcephaly
  • Retardation
  • Seizures
  • Decreased muscle tone
  • Hirschprung's disease (congenital Intestinal blockage)
  • Omphalocoele (abdominal wall defect)
  • Limb defects
  • Hypospadias (urethral is not located at tip of penis)
  • Cardiac defects
  • Miscarriage
  • Facial anomalies such as micrognathia (small jaw), external ear anomalies, microphthalmia, (small eye development) and midface hypoplasia (underdevelopment of the middle of the face)

Some recent studies (2003 by Hertz-Picciotto) are skeptical about attributing hot tub use with miscarriage. Poorly designed studies with low numbers of participating subjects, lack of stratification of data based on age of the pregnant women that participated in the studies, (older mothers have more of a tendency towards miscarriage anyway) along with some inconsistencies in the findings, prevent definite links between hot tub use and miscarriage.

What Causes These Anomalies?

Facial features and the neural tube regions form occur from week 4 to week 16 in utero. This is the critical time in development where these organ systems can be affected by elevated maternal temperatures.