TABLE 1.

Reference ranges of trimester‐specific levels of fibrinogen, D‐dimer and activated partial thromboplastin time (aPTT) in pregnancy (from Cunningham FG, Leveno KJ, Bloom SL, Hauth JC, Rouse DJ, Spong CY. Williams Obstetrics, 23rd Ed. New York (NY): McGraw‐Hill Professional, 2009, with permission from the publisher).(with permission from the publisher) ⁵¹

	1st trimester	2nd trimester	3rd trimester
Fibrinogen (g/L)	2.4‐5.1	2.9‐5.4	3.7‐6.2
D‐dimer (μg/mL)	0.05‐0.95	0.32‐1.29	0.13‐1.7
Activated partial thromboplastin time [aPTT] (seconds)	24.3‐38.9	24.2‐38.1	24.7‐35.0