Inherited antithrombin deficiency and pregnancy: maternal and fetal outcomes

To describe the outcome of pregnancy in women with inherited antithrombin (AT) deficiency.

A descriptive retrospective study was performed. Medical records were reviewed in order to collect data about maternal thrombotic complications and pregnancy outcomes. All women with known inherited AT deficiency and at least one pregnancy looked after at the Vall d'Hebron University Hospital were included. Relatives with known AT deficiency but no pregnancies looked after in our institution were excluded. Eighteen pregnancies were registered among nine AT-deficient women during 1991-2005. This cohort included women without antithrombotic treatment because AT deficiency was not known at the time of their pregnancies.

In 12 pregnancies (66.7%) anticoagulant therapy with low-molecular weight heparin was given, while not in the other six (33.3%) because AT deficiency was not known at this time. Three episodes of venous thromboembolism were recorded (16.7%). Among all pregnancies 10 suffered an adverse outcome (55.6%), including miscarriage (11.1%), stillbirth (11.1%), intrauterine growth restriction (33.3%), placental abruption (6.7%), preeclampsia (6.7%) and intrapartum fetal distress (23.1%). No relation between AT activity and pregnancy complications was found. A lower incidence of pregnancy complications was observed among women with antithrombotic treatment.

Inherited antithrombin deficiency is associated with a high risk of venous thromboembolism during pregnancy and the puerperium. We also observed a high incidence of poor pregnancy outcome among AT-deficient women.