Abstract
Background: Gestational thrombocytopenia (GT) is detected in approximately 8% of healthy pregnant women and > 70% of pregnancy-associated thrombocytopenia cases. Diagnosed by exclusion, GT is primarily a benign disorder of unclear pathogenesis, although mechanisms have been proposed such as hemodilution. To better understand GT, we conducted retrospective longitudinal and cross-sectional analyses of variations in platelet count (PC) during gestation period. Methods: PC kinetics was assessed across a test group of 100 pregnant women, accurately representative of 341 in total, and in a control group of 200 non-pregnant women. Results: In the test group, median PC was comparable to the control group in early gestation but decreased by 8% by delivery day (DD). PC decreased by
> 5% in 59 pregnancies and increased by
> 5% in 19. 12 cases were thrombocytopenic. Median PC fluctuation, 2.5th percentile, and 97.5th percentile were each most extreme in final 5 weeks. Longitudinal analysis established five gestational pattern types defined by curvature and Change Ratio. The GT-type pattern (8 cases) showed relatively low PC in early gestation, mild downwards slope in the 2nd trimester, one or more peaks or “lifts” in the final weeks, followed by a “V-shape” of decrease beyond 15 x 104/μL to DD and sharp post-partum increase. Some of the GT-associated characteristics above appeared identifiable in a majority of pregnancies regardless of absolute PC value: Distinct PC “lift” occurring within the final ten weeks [later than in GT cases] followed by the V-shape [decrease to DD less pronounced than in GT], suggesting that diverse PC kinetics relate to the placental cytokine and receptor system. Conclusion: Our novel identification of diverse kinetic patterns in platelet count over gestational period suggests that, instead of a universal decrease caused by hemodilution alone, homeostatic conditions are affected by a diversity of varying factors such as the placental thrombopoietic system.
