Hemodynamic changes in fetal lamb in uteroin response to asphyxia, hypoxia, and hypercapnia.

• "When fetaJ asphyxia or hypoxia is induced by reduction of uterine and umbilical circulations oi" by administration of a gas mixture of low oxygen content to the mother, there is an increase in the fetal arterial pressure." The effects on the fetal heart rate appear to be variable. Bradycardia has been observed by several investigators.*~ Born et al. noted that the changes in heart rate depended on the degree of hypoxia; when hypoxia was '' moderate,'' tachycardia occurred. Only when the oxygen lack became severe was there bradyeardia. Reynolds and Paul found that the changes in the fetal heart rate during hypoxia were variable, slow rates usually being associated with, more severe hypoxic states.