Influence of maternal hyperventilation on the newborn infant

Moderate controlled hyperventilation during cesarean section can cause the fetus to have slightly less acidosis at birth. However, if maternal PCO2 is lowered below 17 mm. Hg, the infant is likely to have severe acidosis and delayed onset of respiration. Although hyperventilation was not always accompanied by maternal alkalosis in this study, 1 of the two mothers with the most alkalosis belonged to the group in which the anesthesiologist was attempting to maintain a normal level of ventilation. There is danger not for the conscious patient hyperventilating voluntarily, but for the unconscious patient who undergoes artificial ventilation after receiving muscle relaxants. Considerable caution should be exercised, therefore, in the ventilation of pregnant women who undergo cesarean section when muscle relaxants are being used; willful overventilation should be avoided.