Strenuous exercise during pregnancy: is there a limit?

Am J Obstet Gynecol. 2012 Sep;207(3):179.e1-6. doi: 10.1016/j.ajog.2012.07.021. Epub 2012 Jul 20.


Objective: The purpose of this study was to evaluate fetal responses to strenuous exercise in physically active and inactive women.

Study design: Forty-five healthy women (15 who were nonexercisers, 15 who were regularly active, 15 who were highly active) underwent a peak treadmill test at 28 weeks' gestation to 32 weeks 6 days' gestation. Fetal well-being (umbilical artery Doppler indices, fetal heart tracing/rate, biophysical profile [BPP]) was evaluated before and after exercise. Uterine artery Doppler scans were also obtained.

Results: Umbilical and uterine artery Doppler indices were similar among activity groups and did not change with exercise (P > .05). BPP and fetal heart tracings were reassuring in all groups. However, subgroup analyses showed transient fetal heart rate decelerations after exercise and elevated umbilical and uterine artery Doppler indices in 5 highly active women. After this, BPP and fetal heart tracings were reassuring.

Conclusion: Overall fetal well-being is reassuring after short-duration, strenuous exercise in both active and inactive pregnant women. A subset of highly active women experienced transient fetal heart rate decelerations and Doppler changes immediately after exercise. Athletes may push beyond a threshold intensity at which fetal well-being may be compromised. However, potential impact on neonatal outcomes is unknown.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Exercise / physiology*
  • Exercise Test
  • Female
  • Fetus / physiology*
  • Heart Rate, Fetal
  • Humans
  • Pregnancy
  • Ultrasonography, Prenatal
  • Umbilical Arteries / diagnostic imaging
  • Umbilical Arteries / physiology
  • Uterine Artery / ultrastructure