Change of the initiation time of blood coagulation in pregnancy from 10-months to postpartum.

We measured the time of initiation of blood coagulation (Ti) from pregnancy 10-months (36~40 weeks) till 1-month after delivery, paying particular attention to the very early postpartum period, using a damped oscillation rheometer that is approximately 160 times more sensitive than the Thromboelastogram® to evaluate the risk of thrombus formation. Blood samples were obtained from healthy volunteers at pregnancy 10-month, 1-hour, 3-hours, 4-days, 7-days, 3-weeks and 1-month after delivery. Ti values at pregnancy 10-month, 1-hour, 3-hours, 4-days, 7-days, 3-weeks, 1-month after delivery and in non-pregnant females were 20.4 ± 2.2, 11.7 ± 1.6, 13.2 ± 3.1, 17.2 ± 2.0, 20.2 ± 1.6, 21.4 ± 4.0, 24.6 ± 3.6, and (25.0 ± 3.4) minutes, respectively. Ti was significantly shorter at pregnancy 10-month, 1-hour, 3-ours, 4-days, 7-days and 3-weeks after delivery than in non-pregnant females. These data show that the blood of pregnant females is more hypercoagulable than non-pregnant females from pregnancy 10-month until 3-weeks post delivery, suggesting that they are at high risk of VTE after discharge from hospital.