<![CDATA[Background: Spinal anaesthesia-induced hypotension is common during caesarean delivery, and the optimal phenylephrine dosing strategy for obese parturients remains uncertain. This systematic review evaluated the efficacy and dosing regimens of prophylactic phenylephrine infusion in this population. Methods: PubMed, ScienceDirect, the Cochrane Library, and Scopus were searched for randomised controlled trials published from 2010 through 2025. Eligible studies included parturients with singleton pregnancies at ≥36 weeks of gestation, a body mass index ≥30 kg/m², and no major comorbidities. Phenylephrine infusion was compared with bolus regimens or alternative infusion doses. The primary outcome was maternal hypotension; secondary outcomes included reactive hypertension, maternal adverse effects, and neonatal outcomes. Risk of bias was assessed using Cochrane RoB 2, and findings were synthesised narratively because of clinical and methodological heterogeneity. Results: Three randomised controlled trials involving 334 parturients were included. Phenylephrine infusion was associated with fewer hypotensive episodes than bolus administration, although the certainty of evidence was low. One dose-response trial reported preliminary ED₅₀ and ED₉₀ estimates of 0.42 and 0.68 µg/kg/min, respectively. Higher infusion doses were associated with more reactive hypertension, whereas bradycardia did not differ significantly across groups. Nausea, vomiting, and neonatal outcomes showed no consistent between-group differences. Conclusion: The certainty of evidence was low for most outcomes, precluding firm conclusions about the efficacy and optimal dosing of phenylephrine infusion in obese parturients without major comorbidities. Reactive hypertension increased with higher infusion doses, whereas evidence for bradycardia and neonatal safety remained limited. Larger, standardised trials are needed, particularly in parturients with severe obesity or comorbidities.]]>
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