Fifteen trials were included in the review (742 women). The authors reported that most of trials had a low risk of bias. No further results on risk of bias were reported (either in the paper or supplementary materials).
Prevention of hypotension: There were no significant differences between patients receiving ephedrine and those receiving phenylephrine for the incidence of hypotension (seven RCTs), umbilical arterial pH values (two RCTs) and venous pH values (four RCTs). Substantial heterogeneity was observed for the outcomes of hypotension (Ι²=67%) and umbilical arterial pH values (Ι²=92%).
Treatment of hypotension: Pregnant women who received phenylephrine had neonates with higher umbilical arterial pH values (SMD -1.32, 95% CI -2.35 to -0.30; five trials) and venous pH values (SMD -0.79, 95% CI -1.09 to -0.49; four trials) compared with women who received ephedrine. There was no significant difference in the incidence of intra-operative hypotension between the two groups. Substantial heterogeneity was observed for the outcome of umbilical arterial pH values (Ι²=91%).
Results of sensitivity and subgroup analyses were also reported.
The funnel plot suggested the presence of publication bias, but Egger’s and Begg’s tests did not show the evidence of publication bias.