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

The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians

PubMedID: 12820836

Lindqvist PG, Marsal K, Merlo J, Pirhonen JP. Thermal response to submaximal exercise before, during and after pregnancy: a longitudinal study. J Matern Fetal Neonatal Med. 2003;13(3):152-6.
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.