title: Thermal response to submaximal exercise before, during and after pregnancy: a longitudinal study.
abstract: 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).
  
  
  CONCLUSIONS
  During submaximal exercise the temperature response seemed to provide thermal protection for the embryo and the fetus.
authors.affiliation: Department of Obstetrics and Gynecology, Lund University, University Hospital, Malmö, Sweden.
authors.forename: P G
authors.initials: PG
authors.lastname: Lindqvist
authors.forename: K
authors.initials: K
authors.lastname: Marsal
authors.forename: J
authors.initials: J
authors.lastname: Merlo
authors.forename: J P
authors.initials: JP
authors.lastname: Pirhonen
mesh_terms: D000328:Adult; D001831:Body Temperature; D001833:Body Temperature Regulation / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005865:Gestational Age; D006358:Hot Temperature; D006801:Humans; D008137:Longitudinal Studies; D049590:Postpartum Period; D011247:Pregnancy / Q000502:physiology*; D012016:Reference Values