Production of fetal asphyxia by maternal psychological stress

Several lines of evidence indicate that maternal psychological stress leads to adverse pregnancy outcome in rhesus monkey. Chronic anxiety causes an increased stillbirth rate, fetal growth retardation, and altered placental morphology. On another time scale, lightening of maternal anesthesia during surgery produces an impaired fetal oxygenation while re-institution of anesthesia ameliorates the fetal asphyxia. The present study, for the first time, demonstrates a relationship between specific episodes of meternal psychological stress and exacerbation of fetal asphyxia in utero. Eight term pregnant rhesus monkeys were anesthetized with sodium pentobarbital. Catheters were placed both into the maternal and the fetal femoral arteries for the continuous recording of blood pressure and heart rate and for the intermittent campling of maternal and fetal blood. An open-ended catheter recorded intrauterine pressures. Following a complete repair, the anesthesia of the mothers was allowed to lighten. As the mothers awakened, the fetuses invariably showed the developemnt of fetal asphyxia. A fetal acidosis developed and the fetal oxygenation and repair of acidosis. Studies while the mothers were fully awake showed the repeated and regular development of episodes of heightened fetal asphyxia produced by episodes of stressful stimulation of the mothers. Episodes of maternal psychological stress led to changes in both fetal vital signs and blood chemical findings. These alterations in fetal state regularly followed the onset of the episodes of psychological stress by 50 seconds. These changes also usually remitted 50 seconds following the termination of the periods of stress. These results demonstrated a direct and unequivocal relationship between meternal psychological stress and fetal asphyxia. It is assumed the maternal stress produces impairments in the circulation to the uterus through an increased sympathetic nervous system activity and a shunting of the maternal blood-flow from the abdominal viscera to other organs as occurs in the fight-orflight reaction.