Pregnancy-induced antithrombin deficiency.

OBJECTIVE

This retrospective study was performed to characterize the laboratory features and water metabolism of women with pregnancy-induced antithrombin deficiency (PIATD).

METHODS

Among 1493 women who gave birth to a singleton infant at our institution, 114 women who developed PIATD and/or pregnancy-induced hypertension (PIH) were reviewed with respect to perinatal changes in laboratory variables (hematocrit value, fibrinogen, fibrinogen degradation product, D-dimer, uric acid, aspartate aminotransferase, lactate dehydrogenase) and body weight. PIATD was defined as a gradual decline in antithrombin (AT) activity to <or=65% of normal activity levels. One hundred and fourteen women with neither PIATD nor PIH and matched for the cesarean delivery rate were selected as a control group.

RESULTS

Of the 81 women who developed PIH, 19 (23.4%) also developed PIATD. Thirty-three women developed PIATD in the absence of PIH. Coagulation-fibrinolysis was significantly more enhanced and the postpartum reduction in the hematocrit value was significantly larger in women with PIATD, irrespective of the presence or absence of hypertension, than in women without PIATD. The postpartum decrease in body weight was significantly smaller in women with PIATD, irrespective of the presence or absence of hypertension.

CONCLUSIONS

A decrease in AT activity may occur in the absence of hypertension. Even in the absence of hypertension, a decreased plasma volume and enhanced coagulation-fibrinolysis seem to characterize women with PIATD. The monitoring of AT activity may help in distinguishing pregnant women with these insidious risks.