Thermal response to submaximal exercise before, during and after pregnancy: a longitudinal study

J Matern Fetal Neonatal Med. 2003 Mar;13(3):152-6. doi: 10.1080/jmf.


Background: Heat stress in early pregnancy is known to have a teratogenic effect. Exercise produces excess heat and during pregnancy might therefore present a theoretical risk of malformations. Our aim was to assess the thermal response to exercise of healthy pregnant women in a longitudinal study.

Methods: Fourteen women were examined before pregnancy, and followed five times during, and twice after pregnancy, using a submaximal bicycle test with a target heart rate of 85% of the predicted age-adjusted maximum. The main aim was to present reference values.

Results: The temperature at submaximal work load declined continuously from preconception to postpartum levels (37.8 degrees C vs. 36.9 degrees C, p = 0.04). The difference between peak and basal core temperature fell from 0.6 degrees C to 0.05 degrees C at 29 and 36 weeks of gestation, reaching preconception levels at 24 weeks after delivery (0.8 degrees C lower).

Conclusion: During submaximal exercise the temperature response seemed to provide thermal protection for the embryo and the fetus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Body Temperature
  • Body Temperature Regulation / physiology*
  • Exercise / physiology*
  • Exercise Test
  • Female
  • Gestational Age
  • Hot Temperature
  • Humans
  • Longitudinal Studies
  • Postpartum Period
  • Pregnancy / physiology*
  • Reference Values