Serum Sodium Dynamics and Acute Kidney Injury in Pregnancy Associated Sepsis: Insights from Group-Based Trajectory Modeling

BackgroundPregnancy-associated sepsis poses significant maternal, fetal and neonatal risks, with acute kidney injury (AKI) being a critical complication. The dynamic relationship between serum sodium trajectories and AKI in this population remains unclear.MethodsIn this retrospective cohort study, 138 pregnant patients with sepsis were analyzed using the MIMIC-IV 3.1 database. Three serum sodium trajectory groups were identified via group-based trajectory modeling (GBTM). AKI was defined per KDIGO criteria. Analyses employed logistic regression, inverse probability weighting, multivariable adjustments and cubic spline models.ResultsThree distinct trajectories emerged: Group 1 (low initial sodium that subsequently increased, n = 34), Group 2 (stable sodium levels, n = 83), and Group 3 (high sodium levels throughout, n = 21). Groups 1 and 3 exhibited higher AKI incidence (ORs: 4.04 [95%CI: 1.63-9.96] and 3.97 [95%CI: 1.33-11.87], respectively; both p < 0.05), prolonged ICU stay hours(72, 118 vs 47, p < 0.001), and elevated SOFA scores (p = 0.01) compared to Group 2. Cubic spline analysis revealed a U-shaped risk relationship, with AKI incidence rising at sodium levels >145 mmol/L (p-value for overall was 0.037 and for nonlinear was 0.021).ConclusionsDynamic sodium trajectories, particularly low initial sodium that subsequently increased, independently predict AKI and adverse outcomes in pregnancy-associated sepsis.