Prognostic nutritional index as a predictor of fetal growth restriction and adverse perinatal outcomes

Fetal growth restriction (FGR) is a major cause of perinatal morbidity and mortality. Maternal nutritional and inflammatory status may play a role in its development. The Prognostic Nutritional Index (PNI), derived from serum albumin and lymphocyte count, reflects these pathways.

To investigate the association between maternal PNI and FGR and evaluate the predictive performance of first- and third-trimester PNI for FGR and adverse perinatal outcomes.

This retrospective study included 279 singleton pregnancies (151 FGR and 128 controls). FGR was defined as estimated fetal weight below the 3rd percentile. First- and third-trimester PNI values were calculated. Logistic regression identified independent predictors of FGR, and receiver operating characteristic analysis assessed predictive performance.

First- and third-trimester PNI values were significantly lower in the FGR group than in controls (40.10 vs. 44.07, p<0.001; 37.09 vs. 38.36, p=0.002, respectively). Both first-trimester PNI (adjusted OR 0.80, 95% CI 0.73-0.87, p<0.001) and third-trimester PNI (adjusted OR 0.89, 95% CI 0.79-0.99, p=0.034) were independently associated with FGR. First-trimester PNI showed good predictive performance (AUC 0.76, 95% CI 0.70-0.81), with an optimal cut-off of ≤42.10 (70.9% sensitivity and 72.0% specificity), whereas third-trimester PNI showed lower accuracy (AUC 0.64, 95% CI 0.57-0.71). Lower third-trimester PNI was independently associated with preterm delivery among pregnancies complicated by FGR.

Maternal PNI, particularly in the first trimester, was independently associated with FGR and may serve as a simple biomarker for early risk assessment.