Relevance of maternal sodium level for preeclampsia-associated adverse pregnancy outcomes

Objective: To evaluate maternal sodium levels in women with preeclampsia (PE) or at high risk for preeclampsia and their relevance for severe PE-associated adverse pregnancy outcome and remaining pregnancy duration.

Study design: In a retrospective cohort of 198 patients presenting with signs and symptoms of preeclampsia (PE), we investigated maternal sodium level and the sFlt-1/PlGF-ratio within 14 days prior to delivery.

Main outcome measures: In total, 88 patients (44.4%) developed a maternal and/or fetal and neonatal preeclampsia-associated adverse outcome (AO). The median sodium level was lower in the cohort with vs. without AO (136 vs. 137 mmol/l) and correlated negatively with the sFlt-1/PlGF-ratio (r = -0.19, 95% CI: -0.31 to -0.05) in both groups. Logistic regression revealed a significant association of the maternal sodium level with the development of an AO (+1 mmol/l reduced the odds by 21%, [Odds ratio (OR) of 0.79 (95% CI 0.67-0.93), p < 0.01], whereas the sFlt-1/PlGF showed a contrary effect (+10 units OR of 1.05 (95% CI: 1.02-1.08, p < 0.01)). Linear mixed effects models showed consistent results, with sodium level positively associated with the remaining pregnancy duration.

Conclusions: Our results confirm the relevance of decreased maternal sodium level as a severity marker for PE-associated adverse outcomes.