Human fetal respiration. IV. Failure of severe distress to stimulate aspiration of amniotic fluid by the immature human fetus.

Reported herein are studies on fetal breathing, specifically the inhalation of labeled amniotic fluid, by immature human fetuses so severely distressed that they subsequently died in utero. Decreased rather than increased amounts of the amniotic fluid label were found in the lungs of the distressed fetuses compared to the amounts in fetuses of comparable weight that were not distressed. We conclude from this study of the immature human fetus that severe distress depresses rather than stimulates aspiration of amniotic fluid.