Inherited Antithrombin Deficiency and Pregnancy: Maternal and Fetal Outcomes

Abstract

The risk of a venous thromboembolism (VTE) is 4 to 5 times higher among pregnant women than nonpregnant women. Although studies have shown an association between different thrombophilias and pregnancy complications, several extensive reviews and meta-analyses published in the last decade did not find a relationship between inherited thrombophilias and adverse pregnancy outcomes. Antithrombin (AT) deficiency is uncommon among the inherited thrombophilias, and published data on its influence on pregnancy outcome are limited and controversial. This descriptive retrospective study investigated the effects of inherited AT deficiency on pregnancy outcomes among women with this condition. The participants were 9 women with known inherited AT deficiency and at least one pregnancy who have been managed at the study site, a university hospital in Spain. Data on maternal thrombotic complications and pregnancy outcomes among women with AT deficiency were obtained from the hospital medical records. Relatives with known AT deficiency who had no pregnancies managed at the study site were excluded. During the study period, the 9 women with inherited AT deficiency had 18 spontaneous gestations. In 12 (66.7%) of the 18 pregnancies, the women received anticoagulant therapy with low-molecular weight heparin. However, the other 6 (33.3%) were not given anticoagulants because AT deficiency was unknown at that time. During pregnancy and the puerperium, 3 (16.7%) episodes of VTE were recorded; none occurred while the woman was taking heparin. Ten adverse outcomes occurred in 6 of the 18 spontaneous pregnancies (33%), including 5 (33.3%) with intrauterine growth restriction, 2 (11.1%) with spontaneous abortion, 2 (11.1%) with stillbirth, 1 each (6.7%) with placental abruption and preeclampsia, and 3 (23.1%) with intrapartum fetal distress; 2 of these events occurred in one pregnancy and 3 events occurred in another. In 4 of the affected pregnancies, the woman was taking heparin. There was no association between AT activity and pregnancy complications. Fewer pregnancy complications were found among women who had received anticoagulant treatment. These findings show a high incidence of late pregnancy complications and poor pregnancy outcomes among AT-deficient women. A high risk of VTE during pregnancy and the puerperium was found in these women. The study is limited by its small sample size owing to the low prevalence of AT deficiency.