Longitudinal Hematologic Dynamics and Obstetric Outcomes in Central India: A Prospective Cohort Study

Background: Pregnancy induces substantial physiological hematologic adaptations, including plasma-volume expansion and changes in hemoglobin, leukocyte, and platelet indices. In Central India, nutritional deficiencies and prevalent hemoglobin disorders may compound these changes and influence obstetric risk. Objective: To characterize longitudinal trajectories of maternal hematologic indices across gestation and evaluate their associations with major obstetric complications in a Central Indian tertiary-care cohort. Methods: This prospective observational cohort study enrolled 1,000 pregnant women at a tertiary-care teaching hospital in Chhattisgarh over a 12-month recruitment period. Serial complete blood counts were obtained at 8–12, 20–24, and 32–36 weeks. Primary outcomes were hypertensive disorders of pregnancy (HDP) and postpartum hemorrhage (PPH); secondary outcomes included preterm delivery, low birth weight, intrauterine growth restriction, and neonatal-unit admission. Group-based trajectory modeling identified hemoglobin trajectories, and multivariable logistic regression estimated adjusted associations with obstetric outcomes. Results: Baseline anemia (Hb <11.0 g/dL) was present in 53.6% of participants. Three hemoglobin trajectories were identified: decline-stable (n=312; 31.2%), physiological dip-rise (n=498; 49.8%), and failure of hemodilution/elevated hemoglobin (n=190; 19.0%). Within the decline-stable group, women with third-trimester Hb <9.0 g/dL had higher PPH risk (14.2% vs. 3.8%; adjusted OR 3.87, 95% CI 2.14–6.99; p<0.001). Failure of hemodilution (second-trimester HCT >36%) was associated with preeclampsia (adjusted OR 2.41, 95% CI 1.52–3.82; p<0.001). Progressive thrombocytopenia was associated with severe HDP and greater operative blood loss. Conclusion: Longitudinal hematologic monitoring during pregnancy may provide clinically useful prognostic information for identifying women at increased risk of obstetric complications. External validation is required before trajectory-based risk classification is adopted for routine clinical use.