Preoperative prognostic nutritional index and its impact on surgical-site infection after cesarean section: a retrospective case–control analysis

Abstract Purpose Surgical-site infections (SSI) remain a major complication of cesarean delivery, increasing maternal morbidity, hospital stay, and healthcare costs. Although several risk factors have been identified, the role of maternal nutritional status—particularly the Prognostic Nutritional Index (PNI)—has not been well established in obstetric surgery. Methods This retrospective case–control study included 190 women who underwent cesarean delivery at a tertiary referral center between 2020 and 2025. Preoperative PNI was calculated using serum albumin and lymphocyte counts obtained within 24 h before surgery. SSI was defined according to the Centers for Disease Control and Prevention criteria. Demographic, perioperative, and postoperative variables were analyzed to evaluate associations between PNI, SSI status, infection severity, and inflammatory markers. Results A total of 190 women were analyzed, including 98 cases with surgical-site infection (SSI) and 92 controls without SSI. Although preoperative PNI was not an independent predictor of SSI, lower PNI values were associated with more severe infections requiring broad-spectrum antibiotics, longer hospitalization, and higher postoperative C-reactive protein (CRP) levels. A significant inverse correlation was observed between PNI and CRP among patients with SSI ( r = − 0.338, p = 0.001). Longer operative duration and smoking were also associated with an increased risk of SSI. Conclusion Although PNI was not an independent predictor of SSI, lower values were strongly associated with infection severity and systemic inflammation. Integrating PNI into preoperative risk assessment—alongside body mass index and operative time—may help identify high-risk women. Larger prospective studies are warranted to confirm these findings and to evaluate the impact of nutritional optimization on postoperative outcomes.