BACKGROUND: Early-onset pre-eclampsia is associated with severe maternal and perinatal complications. Identifying novel biomarkers for early prediction is crucial for timely intervention and improved outcomes. This study aimed to evaluate the predictive value of platelet parameters, namely mean platelet volume (MPV), platelet distribution width (PDW), and platelet count (PC), for early-onset pre-eclampsia. METHODS: A prospective cohort study was conducted at a tertiary care hospital in Gujarat, India. Pregnant women (n = 712) between 14 and 18 weeks of gestation were enrolled and followed up until delivery. MPV, PDW, and PC were measured at enrollment. The primary outcome was the development of early-onset pre-eclampsia (<
34 weeks). Receiver operating characteristic (ROC) curves were used to evaluate the predictive value of platelet parameters. RESULTS: The prevalence of early-onset pre-eclampsia was 5.3%. Women who developed early-onset pre-eclampsia had significantly higher MPV and PDW and lower PC at 14-18 weeks compared to those who remained normotensive. The combination of MPV >
10.2 fL, PDW >
16.5 fL, and PC <
180 × 103/µL had the highest predictive value (AUC: 0.951, sensitivity: 71.1%, specificity: 99.1%). Individual platelet parameters also demonstrated good predictive ability. CONCLUSION: Platelet parameters, particularly MPV, PDW, and PC, measured at 14-18 weeks of gestation, have good predictive value for early-onset pre-eclampsia. Incorporating these parameters into routine antenatal screening could improve the early identification of at-risk women. Further research is needed to validate these findings and evaluate the cost-effectiveness of implementation.