The effects of hypoxia and hyperoxia on fetal-placental vascular tone and inflammatory cytokine production

Objective: To determine the effects of fetal hypoxia and hyperoxia on placental vascular tone and production of interleukin-6 and tumor necrosis factor-α. Study Design: The maternal and fetal circulation of 2 cotyledons from 5 human placentas were perfused for 4 hours. The fetal circulation of 1 cotyledon was perfused with hypoxic Hanks’ balanced salt solution; the other was perfused with hyperoxic Hanks’ balanced salt solution. Fetal vascular pressures were recorded every 10 minutes, and fetal vein effluents were collected hourly. Results: Fetal-placental vascular perfusion pressure was reduced from baseline during hypoxic conditions. Cytokine concentrations were elevated during hyperoxic conditions compared with hypoxic conditions, with significant differences achieved at 2, 3, and 4 hours for interleukin-6 and at 4 hours for tumor necrosis factor-α. Conclusion: Fetal-placental vasodilation may be a compensatory mechanism to improve hypoxic conditions. Supraphysiologic oxygenation may contribute to the fetal inflammatory response syndrome and to the development of cerebral palsy. (Am J Obstet Gynecol 2001;185:1068-72.)