Effect of Thrombophylaxis on Uterine and Fetal Circulation in Pregnant Women with a History of Pregnancy Complications

Abstract

Purpose: The aim of this study was to investigate the effect of thromboprophylactic therapy on fetal and maternal Doppler flow parameters in pregnant women with severe complications in previous pregnancies and evidence of acquired or congenital thrombophilia in the current pregnancy. Methods: Sixty-five patients with a history of recurrent abortions, intrauterine fetal death, intrauterine growth restriction (IUGR), and severe early-onset preeclampsia were tested for the presence of acquired or congenital thrombophilia. Those with positive findings were prescribed low-dose aspirin plus low-molecular-weight heparin (LMWH) (enoxaparin); the remainder received low-dose aspirin only. A Doppler flow study was performed before and after treatment and in the third trimester of pregnancy. Results: Of the 65 pregnancies, four ended in spontaneous abortion and were excluded from the analysis. Of the 61 women with completed pregnancies, 37 (61%) had evidence of acquired or congenital thrombophilia: 22 (36%) protein S deficiency; 1 (2%) protein C deficiency; 2 (3%) activated protein C resistance (APC-R); 2 (3%) IgG for antiphospholipid antibodies; 1 (2%) circulating anticoagulant; and 9 (15%) a combined defect. This group showed a significant decrease in mean uterine artery pulsatility index (PI) before and after treatment (1.32±0.36 vs. 1.04±0.23, P=.006), whereas the remaining 24 patients treated with low-dose aspirin only had nonsignificant changes. Pearson's correlation test yielded no correlations of the pregnancy outcome parameters with Doppler flow values in the umbilical or uterine arteries. Conclusions: Thromboprophylactic therapy transiently improves maternal circulation parameters in patients with thrombophilia at risk of fetal loss and other severe complications of pregnancy, but not in correlation with their pregnancy outcome. Therefore, Doppler examination of maternofetal circulation in the second trimester is not predictive of pregnancy outcome.