Background To investigate the adverse effects of anticoagulant therapy during pregnancy in a tertiary care center.
Material and methods A prospective study was carried out between 1 January 1977 and 31 December 1994 and included 54 pregnancies in 50 women treated with anticoagulants. In Group I (n=43) oral anticoagulants were replaced for heparin from the sixth until the end of the twelfth week of gestation. In Group II (n= 11) the pregnancy was diagnosed after the ninth week of gestation and acenocoumarol was not substituted. All patients received vitamine K antagonists during the second and third trimesters. Heparin was given after 36 weeks of pregnancy until the tenth day in the postpartum period. Statistical comparisons used Chi square test (with the Yates correction when appropriate) and Student t test. Results. Mechanical heart valve prosthesis was the most frequent indication (68%). There was one artificial heart valve thrombosis during first trimester in Group I and none in Group II (p=0.45). One spontaneous abortion occurred in each group (p=0.86). Seven cardiac complications (13.7%) occurred during the second and third trimesters. We recorded no thrombotic episode of an artificial heart valve after the first trimester of pregnancy. Hemorrhagic complications occurred in mid pregnancy (one case=2%) and during peripartum (eight cases=16%). Two maternal deaths occurred in the postpartum period, both were linked with the anticoagulant therapy. There was one coumarin embryopathy (Group II: 9%), but no neonatal mortality.
Conclusions (1) Hemorrhagic complications occur among 16% of patients receiving anticoagulant therapy during pregnancy. (2) Delivery and postpartum are the most critical periods.