Mean Platelet Volume and Risk of Preeclampsia: A Case-Control Study at the Peruvian National Maternal Perinatal Institute

Background: Platelet activation is central to preeclampsia (PE) pathobiology. We evaluated whether mean platelet volume (MPV) is independently associated with PE and quantified its individual discriminatory performance in a hospital-based case-control study in Peru. Methods: We included 112 women with PE and 112 normotensive controls who delivered at the National Maternal Perinatal Institute (Lima) in 2024. MPV was obtained from the first complete blood count (CBC) performed at ≥20 gestational weeks. Logistic regression models estimated adjusted odds ratios (aORs) with 95% CIs. Receiver operating characteristic (ROC) analysis provided the area under the curve (AUC) with 95% CI and the optimal cutoff by Youden’s index. Results: Higher MPV was independently associated with PE (aOR: 2.16 per 1 fL; 95% CI: 1.55–3.01; p < 0.001). Gestational obesity (aOR: 2.43; 95% CI: 1.17–5.26; p = 0.039) and inadequate prenatal care (<6 visits; aOR: 3.71; 95% CI: 1.27–7.55; p = 0.006) were also associated with PE. MPV showed moderate discrimination (AUC: 0.686; 95% CI: 0.616–0.755). Using a cutoff of 8.80 fL, the sensitivity was 61.6%, the specificity was 71.4%, the positive likelihood ratio was 2.16, and the negative likelihood ratio was 0.54. Conclusions: MPV is independently associated with PE and provides moderate individual discrimination. As MPV is routinely measured by hematology analyzers at no additional cost, incorporating it into trimester-specific, multivariable antenatal risk models may support cost-effective risk stratification in resource-limited settings.