The effect of intrauterine resuscitation by maternal hyperoxygenation on perinatal and maternal outcome; a randomized controlled trial

Abstract Background Maternal hyperoxygenation is widely used during labor as an intrauterine resuscitation technique. However, robust evidence regarding its beneficial effect and potential side effects is scarce and previous studies show conflicting results. Objective To assess the effect of maternal hyperoxygenation upon suspected fetal distress during the second stage of term labor on fetal heart rate (FHR), neonatal outcome, maternal side effects, and mode of delivery. Study design In a single-center randomized controlled trial in a tertiary hospital in The Netherlands, participants were randomized in case of an intermediary or abnormal FHR pattern during the second stage of term labor, to receive either conventional care or 100% oxygen at 10 L/min until delivery. The primary outcome was the change in FHR pattern. Prespecified secondary outcomes were Apgar score, umbilical cord blood gas analysis, neonatal intensive care unit admission, perinatal death, free oxygen radical activity, maternal side effects, and mode of delivery. We performed subgroup analyses for intermediary and abnormal FHR, and for small for gestational age fetuses. Results From March 2016 through April 2018, 117 women were included. FHR patterns could be analyzed in 71 women. Changes in FHR (defined as improvement, equal, or deterioration) in favor of maternal hyperoxygenation were significant (OR 5.7, 95% CI 1.7-19.1) using ordinal logistic regression. Apgar score, umbilical cord blood gas analysis, free oxygen radicals, and mode of delivery showed no significant differences between the intervention and control group. Among women with an abnormal FHR, there were fewer episiotomies on fetal indication in the intervention group (25%) than in the control group (65%, P Conclusion Maternal hyperoxygenation has a positive effect on the FHR in the presence of suspected fetal distress during the second stage of labor. There was no significant difference in the mode of delivery or neonatal outcome, however, significantly fewer episiotomies on fetal indication were performed following maternal hyperoxygenation in the subgroup with abnormal FHR pattern.