Bioelectrical impedance-derived extracellular fluid expansion and perinatal outcomes in preeclampsia

To quantify extracellular fluid expansion in preeclampsia using bioelectrical impedance analysis (BIA) and to evaluate whether BIA-derived extracellular water (ECW) indices are associated with perinatal outcomes.

In this prospective cohort study, 16 hospitalized women with high-risk pregnancies (7 with preeclampsia and 9 normotensive controls) underwent segmental BIA at a mean gestational age of 32 weeks. Total body water (TBW), intracellular water (ICW), ECW, and ECW/TBW were compared between groups. Fluid indices were additionally expressed as weight-adjusted and height-indexed measures. Associations between ECW/TBW and perinatal outcomes were reviewed and analyzed.

Compared with normotensive controls, women with preeclampsia had higher TBW, ICW, ECW, and ECW/TBW (all p < 0.05), with consistent segmental elevations most prominent in the lower extremities. Weight adjustment eliminated between-group differences in absolute fluid volumes, whereas height-indexing preserved significant elevations across compartments (all p ≤ 0.002). In the overall high-risk cohort, higher ECW/TBW was associated with earlier gestational age at delivery and lower 1-minute Apgar scores (both p < 0.05).

Preeclampsia is characterized by measurable extracellular fluid expansion on bedside BIA. Elevated ECW/TBW is associated with adverse perinatal outcomes among hospitalized high-risk pregnancies, supporting the potential clinical utility of non-invasive fluid assessment for risk stratification in hypertensive disorders of pregnancy.