Establishing trimester-specific reference intervals for coagulation parameters in pregnant women in China

BACKGROUND: During pregnancy, the body's hemorrhagic and coagulation system undergoes significant changes. Reference intervals for coagulation parameters may vary across different study populations and with different testing instruments. This study aimed to establish reference intervals for coagulation parameters in non-pregnant and pregnant women in China. METHODS: Between January 2023 and February 2024, blood samples from 879 pregnant women and 253 healthy non-pregnant women were tested. The parameters tested included activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), fibrinogen (FBG), D-dimer, fibrin/fibrinogen degradation products (FDP), Plasminogen (PLG), thrombin-antithrombin complex (TAT), thrombomodulin (TM), plasmin-α2 plasmin inhibitor complex (PIC), and tissue plasminogen activator/plasminogen activator inhibitor-I complex (t-PAIC). Reference intervals were established using a non-parametric method. RESULTS: The values of PT, INR, APTT, and TT decreased, while the concentrations of fibrinogen, D-dimer, FDP, PLG, TM, TAT, PIC, and t-PAIC increased significantly with advancing gestational age. Distinct reference intervals were established for healthy non-pregnant women and for women in the first, second, and third trimesters of pregnancy. Most intervals differed significantly across these groups. CONCLUSIONS: Reference intervals for non-pregnant women and pregnant women in different trimesters vary. Description of the reference intervals according to trimester of pregnant women in China will help clinicians recognise abnormality and inform medical decision-making.