Plasma levels of microparticles at 24 weeks of gestation do not predict subsequent pregnancy complications

Objective: To discern whether plasma levels of microparticles (MPs) measured at 24 weeks of gestation predict late complications of pregnancy. Design: Secondary analysis of samples obtained prospectively. Setting: Large academic medical center. Patient(s): Two hundred sixty-two healthy women selected from 642 nulliparous women with singleton pregnancies. Intervention(s): Sampling for blood cell MPs and thrombophilias at 24 weeks of gestation and measurements of blood flow resistance in uterine, placental, and umbilical arteries at 24 and 31 to 33 weeks of gestation. Main Outcome Measure(s): Relationship between levels of MPs and late pregnancy complications, thrombophilias, and blood flow resistance. Result(s): Flow cytometry only detected MPs derived from endothelial cells (CD31⁺) and platelet (CD41⁺). No statistically significant correlation was found between levels of CD31⁺ or CD41⁺ MPs and subsequent occurrence of pregnancy-induced hypertension, preeclampsia, intrauterine growth restriction, or small for gestational age infants. Nor was there a statistically significant correlation with blood flow resistance parameters at 24 weeks of gestation (except for the left uterine artery) or at 31 to 33 weeks of gestation. Levels of these MPs in thrombophilic and nonthrombophilic women were similar. Conclusion(s): Levels of circulating MPs at 24 weeks of gestation had no predictive value for subsequent development of pregnancy-induced hypertension, preeclampsia, intrauterine growth restriction, or small for gestational age infants.