Spinal analgesia and labor outcomes in low-risk parturients: a single-center retrospective cohort study

To assess the association of a spinal analgesia (SA)-based intrapartum management strategy ("SA framework") with labor progression and selected maternal and neonatal outcomes in low-risk parturients.

This single-center retrospective cohort study included low-risk parturients between June 2024 and February 2026. The primary outcome was prolonged second-stage labor defined using established clinical thresholds. Secondary outcomes were emergency cesarean delivery (ECD) and umbilical arterial pH ≤ 7.10. Associations were estimated using multivariable regression, with a sensitivity analysis adjusting for labor augmentation.

Among 800 parturients, 610 (mean age: 31.83) and 190 (mean age: 32.21) were categorized into the non-SA and SA groups, respectively. The median second-stage labor was significantly longer in the SA group (p < 0.001); however, the SA framework was associated with a reduced risk (aOR 0.314, 95% CI 0.127-0.663) and an absolute risk reduction of 8.6% (95% CI 2.4-14.7%), corresponding to a number needed to treat of approximately 12, with consistent results in sensitivity analyses. More than 90% of parturients in the SA group delivered before reaching threshold durations. Vacuum-assisted delivery was more frequent in the SA group (p < 0.001). The incidences of ECD (1.0%) and low umbilical arterial pH (1.6%) were low. No clear safety signal was identified, although the study was underpowered for rare neonatal outcomes.

The SA framework was associated with lower observed frequency of exceeding predefined thresholds. This apparent paradox may reflect earlier or more frequent obstetric interventions, suggesting a shift in the distribution of labor duration. These findings likely represent a bundled management strategy rather than a direct physiological effect of SA. Further prospective studies are needed to confirm these findings and clarify causal relationships.