Red Cell Distribution Width-to-Albumin Ratio as a Predictor of Preeclampsia in Advanced Maternal Age: A Retrospective...

Preeclampsia is a leading cause of maternal and perinatal morbidity, particularly among women of advanced maternal age. Simple and inexpensive laboratory markers associated with preeclampsia risk remain of clinical interest in this population. The red cell distribution width‑to‑albumin ratio (RAR), an integrated index of erythrocyte anisocytosis and hypoalbuminemia, has emerged as a marker of systemic inflammation and vascular stress in cardiovascular and critical care settings. Its relevance to preeclampsia is unknown.

We conducted a retrospective cohort study of 2296 women aged ≥35 years with singleton pregnancies delivering at a tertiary hospital between 2013 and 2023. Blood samples for red cell distribution width (RDW) and serum albumin were obtained during early pregnancy prenatal visits at 11-12 weeks of gestation. RAR was calculated as red cell distribution width (RDW, %) divided by serum albumin (g/L) and analyzed as RAR multiplied by 10 (RAR×10) and by tertiles. Preeclampsia was confirmed after 20 weeks of gestation. Multivariable logistic regression, restricted cubic splines, and prespecified subgroup analyses were performed to evaluate associations between RAR and preeclampsia.

The mean age was 37.78 ± 2.67 years; 328 women (14.29%) developed preeclampsia. Preeclampsia prevalence increased across RAR tertiles (9.95%, 14.14%, 18.75%; p<0.001). Each one‑unit increase in RAR×10 was associated with higher odds of preeclampsia (adjusted OR 1.16, 95% CI 1.04-1.30). Compared with the lowest tertile, adjusted OR was 1.38 (95% CI 0.98-1.94) for tertile 2 and 1.89 (95% CI 1.35-2.64) for tertile 3, respectively (p for trend<0.001). Restricted cubic spline analysis suggested a non-linear, J‑shaped association, with risk rising steeply above RAR×10≈3.95. The association appeared stronger among women with obesity.

Higher RAR measured in early pregnancy was associated with increased preeclampsia risk in AMA women and may serve as a simple biomarker for early risk stratification.