The effect of maternal hyperoxygenation on fetal circulatory system in normal growth and IUGR fetuses. What we can learn from this impact

Purpose: The objectives of study were to assess and compare the effects of maternal hyperoxygenation on fetal circulation, in fetuses with intrauterine growth retardation and normal fetal growth. Methods: Twelve singleton pregnant women with normal fetal growth and 12 singleton pregnant women with intrauterine growth restriction were recruited. Mean gestational age of 35.2 +/- 3.5 and 34.7 +/- 3.9 weeks, respectively. Doppler blood flow velocity waveforms were obtained from the middle cerebral artery, umbilical, main and proximal right pulmonary arteries. Pulsatility indices were calculated for all the vessels. Peak systolic velocity was determined for the middle cerebral artery. Following baseline measurements; each woman received 70% humidified oxygen for 10 min. Doppler measurements were then repeated. Results: The pulsatility index in the middle cerebral artery increased significantly from 1.5 +/- 0.27 to 1.88 +/- 0.48, respectively (p =.006) in the high-risk group. However, it did not change significantly in the low-risk group. Hyperoxygenation caused a significant decrease in pulsatility indices in the pulmonary arteries for both groups. Conclusions: Hyperoxygenation interrupts the relative brain-sparing effect in the intrauterine growth retardation group, but it did not significantly change the pulsatility index of the middle cerebral artery in fetuses with adequate weight. The pulsatility index in the pulmonary arteries decreased significantly following hyperoxygenation.