What does this research mean for the field?

Overall evidence does not demonstrate the superiority of phenylephrine infusion over bolus dosing for preventing maternal hypotension during cesarean delivery, though fixed-rate prophylactic infusions may reduce hypotension at the cost of increased reactive hypertension. Novelty: ClaimNovelty.SYNTHESIS. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This research aims to determine whether phenylephrine bolus or infusion is more effective in preventing hypotension during cesarean delivery.

March 27, 2026Open Access

Maternal and fetal outcomes of phenylephrine bolus versus infusion during cesarean delivery: A systematic review, meta-analysis, and trial sequential analysis

Key Points

This research aims to determine whether phenylephrine bolus or infusion is more effective in preventing hypotension during cesarean delivery.
Conducted a systematic review and meta-analysis of randomized controlled trials
Included trials comparing phenylephrine bolus and infusion during cesarean delivery
Evaluated primary outcomes such as maternal hypotension and secondary outcomes like bradycardia and neonatal Apgar scores
No significant difference in predelivery hypotension between bolus and infusion (RR 0.95)
Fixed-rate infusion reduced hypotension compared to bolus (RR 0.73)
Infusion increased risk of reactive hypertension, but maternal outcomes were similar
Neonatal outcomes, including Apgar scores and umbilical arterial pH, remained normal
Overall evidence is inconclusive, particularly due to high heterogeneity

Abstract

Abstract Background and Aims: Phenylephrine is widely used to manage postspinal hypotension during cesarean delivery under neuraxial anesthesia. However, the optimal method of administration, bolus or infusion, remains uncertain. Material and Methods: This systematic review and meta-analysis (PROSPERO CRD420251081996) included randomized controlled trials comparing phenylephrine bolus and infusion regimens during cesarean delivery. The primary outcome was maternal hypotension. Secondary outcomes included reactive hypertension, bradycardia, intraoperative nausea and vomiting, and neonatal outcomes such as Apgar scores, umbilical arterial pH, and paO 2 . A random-effects model was used for meta-analysis, and trial sequential analysis (TSA) was performed to evaluate the robustness of the evidence. Results: Twenty randomized controlled trials involving 2742 parturients (bolus n = 1314; infusion n = 1428) were included. Overall, there was no significant difference in predelivery hypotension between infusion and bolus regimens (RR 0.95, 95% CI 0.70–1.30; I² =94%). However, in a subgroup of fixed-rate infusions, a reduction in hypotension was observed compared with bolus (RR 0.73; 95% CI 0.61–0.88). Infusion was associated with a higher risk of reactive hypertension, while bradycardia and other maternal outcomes were similar. Although Apgar scores and UA pH showed minor statistical differences, all neonatal values remained within normal clinical ranges. TSA confirmed sufficient evidence only for the fixed-rate infusion subgroup; the overall pooled estimate remained inconclusive. Conclusions: Phenylephrine infusion, particularly fixed-rate prophylactic infusion, may reduce hypotension, but the overall evidence does not demonstrate superiority over bolus dosing. Given the very high heterogeneity and increased reactive hypertension with infusion, results should be interpreted cautiously. Neonatal outcomes were clinically comparable between groups.

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