ABSTRACT
Physiological changes in hemostasis during pregnancy have been reported by several authors. This study aimed at establishing reference intervals for the hemostasis biomarkers thrombin-antithrombin complex (TAT), α2-plasmininhibitor-plasmin complex (PIC), thrombomodulin (TM) and tissue plasminogen activator-inhibitor complex (tPAI-C), in healthy pregnancies. After excluding outliers, a total of 496 healthy pregnant women (128 first-trimester, 142 second-trimester, 107 third-trimester and 119 pre-labor) and 103 healthy nonpregnant women were enrolled from Shenzhen Bao'an Women's and Children's Hospital. Hemostasis biomarkers, TAT, PIC, TM and tPAI-C, were measured by using a quantitative chemiluminescence enzyme immunoassay performed on HISCL automated analysers. The median and reference intervals (the 2.5th and 97.5th percentiles) were calculated to establish trimester-specific reference intervals for healthy pregnant women. The reference intervals for TAT, PIC, TM and tPAI-C in the first trimester were 0.7-7.6 1 µg/L, 0.2-0.9 mg/L, 2.8-11.0 TU/ml, and 1.2-6.5 1 µg/L, respectively. The reference intervals in the second trimester were 1.7-12.0 1 µg/L, 0.2-1.0 mg/L, 3.7-11.6 TU/ml, and 2.8-8.8 1 µg/L, respectively. The reference intervals in the third trimester were 2.7-16.1 1 µg/L, 0.1-1.4 mg/L, 2.9-12.9 TU/ml, and 1.9-8.0 1 µg/L, respectively. At pre-labor, the reference intervals were 4.8-32.9 1 µg/L, 0.2-1.9 mg/L, 4.2-12.6 TU/ml, and 2.8-15.4 1 µg/L, respectively. Gestational reference intervals for TAT, PIC, TM and tPAI-C in healthy pregnancies are provided, but only for TAT with increasing concentrations throughout pregnancy, the reference intervals for non-pregnant were not applicable.