Background: Maternal oxygen administration has been used in an attempt to lessen fetal distress by increasing the available oxygen from the mother. This has been used for suspected fetal distress during labour, and prophylactically during the second stage of labour on the assumption that the second stage is a time of high risk for fetal distress.
Objectives: The objective of this review was to assess the effects of maternal oxygenation for fetal distress during labour and to assess the effects of prophylactic oxygen therapy during the second stage of labour on perinatal outcome.
Search strategy: We searched the Cochrane Pregnancy and Childbirth Group trials register (March 2003) and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3, 2002).
Selection criteria: Randomised trials comparing maternal oxygen administration for fetal distress during labour and prophylactic oxygen administration during the second stage of labour with a control group (dummy or no oxygen therapy).
Data collection and analysis: Both reviewers assessed eligibility and trial quality. Data were extracted, checked and entered into RevMan software. For dichotomous data, relative risks (RR) and 95% confidence intervals (CI) were calculated. For continuous data, weighted mean differences and 95% CI were calculated.
Main results: No trials addressing maternal oxygen therapy for fetal distress were located. Two trials which addressed prophylactic oxygen administration during labour were included. Abnormal cord blood pH values (less than 7.2) were recorded significantly more frequently in the oxygenation group than the control group (relative risk 3.51, 95% confidence interval 1.34 to 9.19). There were no other statistically significant differences between the groups. There were conflicting conclusions on the effect of the duration of oxygen administration on umbilical artery pH values between the two trials.
Reviewer's conclusions: Implications for practiceThere is not enough evidence to support the use of prophylactic oxygen therapy for women in labour, nor to evaluate its effectiveness for fetal distress. Implications for researchIn view of the widespread use of oxygen administration during labour and the possibility that it may be ineffective or harmful, there is an urgent need for randomised trials to assess its effects.