Non-reassuring fetal status and neonatal outcome after non-elective caesarean section under spinal anaesthesia: a mediating effect of post-spinal hypotension

To examine both the direct and mediating effects of post-spinal hypotension in the relationship between non-reassuring fetal status (NRFS) and adverse neonatal outcomes. This secondary analysis of a previously conducted prospective observational study included term pregnant women in labor who underwent non-elective emergency caesarean sections under spinal anaesthesia. The indication for caesarean section was categorized as either NRFS or non-NRFS. The primary outcome measure for this study was adverse neonatal outcome, defined as a composite of neonatal resuscitation required immediately after delivery, a 1-minute Apgar score < 7, a 5-minute Apgar score < 7, neonatal intensive care unit admission, or in-hospital death within 7 days. Causal mediation analysis was used to investigate the relationships between NRFS, post-spinal hypotension, and adverse neonatal outcomes. Out of the 335 parturients, post-spinal hypotension occurred in 155 (46%), and adverse neonatal events were observed in 56 newborns (16%). Causal mediation analysis showed that both total and direct associations between NRFS and adverse neonatal outcomes remained significant after adjusting for confounders. However, the indirect effect through post-spinal maternal hypotension was not significant. In multivariable logistic regression analysis, NRFS and post-spinal hypotension were independently associated with adverse neonatal outcomes, with odds ratios of 10.26 (95% CI, 4.13 to 25.48; P < 0.001) and 2.03 (95% CI, 1.01 to 4.07; P = 0.044), respectively. We found no evidence that post-spinal hypotension mediated the association between NRFS and composite adverse neonatal outcomes in non-elective cesarean section, although NRFS and post-spinal hypotension were each independently associated with these outcomes.