Effects of hypoxemic events on breathing, body movements, and heart rate variation: a study in growth-retarded human fetuses.

In 14 growth-retarded human fetuses, breathing and body movements were studied before, during, and after late heart rate decelerations. Heart rate variation was measured before and after the decelerations. Breathing and body movements were significantly reduced during and after the deceleration. Heart rate variation was reduced after the decelerative episode. Since late heart rate decelerations are presumably signs of acute fetal hypoxemia, there is evidence that these reductions are caused by hypoxemia. The results suggest, furthermore, that just as in fetal sheep, these changes might be mediated by a change in brain activity state.