[Use of anticoagulants during pregnancy]

Prolonged anticoagulant therapy may be indicated during pregnancy in patients with inborn diseases affecting haemostasis, mechanical heart valves, etc. A management scheme aimed at protecting both the mother and the foetus is presented on the basis of pharmacological data, the main series reported in the literature and the experience acquired at the Boucicaut hospital in Paris. Heparin should be used during the first trimester of pregnancy to avoid the teratogenic potential of antivitamin K drugs and to reduce the incidence of spontaneous abortions which increases in patients given oral anticoagulants. During the second and third trimester, antivitamin K drugs can be used more easily than heparin with no substantial increase in risk for the foetus. At delivery and during the immediate post partum period it is imperative to use a compound which does not cross the placental barrier (in order to avoid foetal hypocoagulation) and which has a short half-life. Heparin is therefore indicated again starting at eight months gestation. It is emphasized that despite careful management and follow-up by the co-ordinated efforts of cardiologists, obstetricians and the intensive care team haemorrhage occurs in 17% of the pregnant women given anticoagulants, particularly during the peri partum period.