Measuring physiological changes in pregnant women during hot yoga

Abstract

One of the concerns surrounding the practice of hot yoga is a potentially dangerous increase in core temperature, notably pregnant women. Previous research has shown that a core temperature in excess of 102.2 ºF, or an increase in core temperature greater than 2.7-3.6 ºF from rest, may result in abnormal fetal development. The main purpose of this study was to evaluate and compare the core temperature responses in pregnant and non-pregnant women during a 60- minute hot-yoga class. Four pregnant and five non-pregnant women served as subjects and all subjects were regular participants in hot yoga. Prior to the class, subjects ingested a CorTemp Ingestible Core Body Temperature Sensor (HQ Inc, Palmetto, FL). Core temperature was recorded every 10 minutes during the class. Room temperature and humidity averaged 95.7ºF and 56.7% respectively, during the class. The highest core temperature recorded during a class averaged 99.5 ºF in the pregnant subjects and 99.9 ºF for the non-pregnant subjects. The highest single core temperature in a pregnant subject was 100.1 ºF, while one non-pregnant volunteer reached 101.4ºF. None of the pregnant subjects had a change in core temperature during a class in excess of 1.2ºF and the largest change for a non-pregnant subject was 2.8 ºF. Based upon the results of this study, it appears that women who are participating in hot yoga at the time of their pregnancy can safely continue their practice. However, it is still not recommended that women start a yoga practice after they become pregnant.