Antithrombin III Levels in Normotensive and Hypertensive Pregnancy

Abstract

Antithrombin III (AT III) is the main physiological inhibitor of blood coagulation. In a prospective study, plasma AT III was determined in 653 women during pregnancy, using an automated amidolytic technique. A control value 8 weeks after delivery was obtained in 192 of the women. In women with pregnancy-induced or aggravated hypertension a significant decrease in AT III levels was observed compared with normotensive controls of the same period of gestation and compared with the patients’ own control values 6–8 weeks after delivery. No AT III depression occurred in patients with chronic hypertension during pregnancy. Patients with pregnancy hypertension and proteinuria had lower AT III levels than those without proteinuria, whose AT III levels were also depressed. Lowest AT III levels were seen in 2 eclamptic patients and in patients with severe preeclampsia, whose pregnancies were terminated for fetal distress while the infants were still preterm. Monitoring AT III levels is of value in preeclampsia.

Association of Antithrombin Activity with Plasma Aldosterone Concentration and Plasma Renin Activity in Pregnant Women

“…Although difference did not reach a significant level mainly due to a small number of study subjects with hypertension in this study, a reduced AT activity is one of the laboratory characteristics seen in women with preeclampsia, eclampsia, and HELLP syndrome [1][2][3][4]19]. Six out of 11 women with eclampsia exhibited a reduced AT activity of less than 65% of the normal activity level before or soon after an eclamptic fit [21].…”

“…Women with hypertension are likely to show a decreased AT activity [1][2][3]. Some pregnant women without hypertension, however, also develop a gradual decline in AT activity (normal reference range, 80% -120%) during the late stage of pregnancy, even in the absence of hypertension [4,5], and the 10 th , 3 rd , and 1 st percentile values of AT activity are 74%, 69%, and 66% of the normal activity level, respectively, in otherwise healthy women immediately before undergoing vaginal delivery [6].…”

Postpartal Right Ventricular Thrombosis

“…Other factors predisposing to peripartal thrombosis include elderly pregnant women, obesity, and a positive family history in terms of thrombosis. The increased production of thrombin during preeclampsia is considered to be related to a prothrombotic condition [2,3]. Bergqvist et al first described the connection between cesarean delivery and an increased incidence of thrombosis (1.8%) [4].…”

The role of serotonin in the preeclampsia-eclampsia syndrome

“…In women who have been observed progressively and who develop preeclampsia, the increased consumption occurs prior to the onset of clinically evident disease. Antithrombin III activity is characteristically reduced in women with preeclampsia secondary to increased consumption [52][53][54]. The decline in antithrombin III activity occurs in at least some patients prior to the onset of clinically apparent disease [52,53].…”

“…Antithrombin III activity is characteristically reduced in women with preeclampsia secondary to increased consumption [52][53][54]. The decline in antithrombin III activity occurs in at least some patients prior to the onset of clinically apparent disease [52,53]. None of these clotting abnormalities has been repetitively demonstrated in pregnant women with nonpreeclamptic hypertension.…”