Comparative Effectiveness of Prophylactic Vasopressors During Elective Cesarean Delivery Under Neuraxial Anesthesia: A Systematic Review With Network-Based Quantitative Synthesis

Cesarean delivery is commonly performed under spinal anesthesia because of its rapid onset, effective analgesia, and favorable maternal-fetal safety profile. Postspinal hypotension, however, remains a frequent complication and may result in maternal symptoms and impaired uteroplacental perfusion. Vasopressors such as phenylephrine, norepinephrine, and ephedrine are routinely used for prophylaxis, yet the optimal agent in low-risk parturients remains uncertain. This study compared the effectiveness and safety of commonly used prophylactic vasopressors in low-risk women undergoing elective cesarean delivery under spinal anesthesia. PubMed, Embase, CENTRAL, and ClinicalTrials.gov were systematically searched from inception to May 2025, and the protocol was registered on PROSPERO (CRD420251060720). Randomized controlled trials comparing norepinephrine, phenylephrine, ephedrine, or placebo were included. In total, 42 trials involving 4,534 participants met the eligibility criteria. A network meta-analysis using odds ratios with 95% confidence intervals was conducted, and treatments were ranked using the surface under the cumulative ranking curve values. Compared with placebo, vasopressors showed a non-significant trend toward preventing postspinal hypotension. Norepinephrine ranked highest for favorable maternal hemodynamic outcomes and prevention of bradycardia, followed by phenylephrine and ephedrine. No significant differences were observed in neonatal Apgar scores or maternal nausea and vomiting. Overall, while statistical superiority was not demonstrated, norepinephrine consistently ranked highest for maternal hemodynamic stability in low-risk parturients.