Meta-analysis of reference values of haemostatic markers during pregnancy and childbirth

Previously reported haemostatic reference intervals in normal pregnancy displayed considerable contradictions to establish convince gestational age-related haemostatic reference values. 30 clinical reports were recruited to collect and assemble existing clinical reports from the database D-dimer levels increased progressively with gestational ages and exceeded conventional value of 1 mg/L after 29–36 weeks, and reached a peak at 24 h postpartum with mean value of 6.44 mg/L [95% confidence interval (CI): 5.84 to 7.05] and returned to 0.79 mg/L (95% CI: 0.43 to 1.16) at 1–8 weeks postpartum. Analogously, the level of fibrinogen gradually increased throughout the pregnancy, and peaked at 48–72 h after birth, with mean value of 9.05 g/L (95% CI: 2.22 to 15.89) and then returned to 3.62 g/L (95% CI: 3.03 to 4.20) at 1–8 weeks postpartum. However, in the middle trimester, asynchronously prothromb in fragments 1 + 2 (F1+2) level elevated and reached a peak at 28–36 weeks with mean value of 3.05 nmol/L (95% CI: 2.41 to 3.70), and then decreased in the later trimester, and reached 1.92 nmol/L (95% CI: 0.58 to 3.27) at 48–72 h post-partum, close to normal levels. Previously reported gestational age-related haemostatic reference intervals in pregnancy could not be used as a standard.