Table 1.

Anticoagulation regimen in pregnant women with mechanical prosthetic valves.

Pre-pregnancy

– Discuss anticoagulation regimen with the patient

– Continue coumarin derivative until pregnancy is achieved

– When menstruation does not occur at expected day, perform pregnancy tests every 3 days until positive or until menstruation, in order to detect pregnancy at early stage

– Instruct patient to contact physician responsible for anticoagulation as soon as pregnancy is achieved

– Give patient and physician responsible for anticoagulation written instructions about anticoagulation regimen during pregnancy

6th to 12th week of pregnancy

– If warfarin daily dose is <5 mg or acenocoumarol dose <2.0 mg, consider continuation of coumarin derivative throughout pregnancy

– Otherwise, substitute coumarin derivative with subcutaneous LMWH twice daily

– Adjust LMWH dose to achieve peak anti-Xa levels of 0.7 to 1.2 U/l ml 4 hours post dose

– If trough levels are subtherapeutic with therapeutic peak levels, dose 3 times daily

– Check anti-Xa levels weekly

13th to 35th week of pregnancy

– Resume coumarin derivative

36th week of pregnancy

– Substitute coumarin derivative with subcutaneous LMWH twice daily

– Adjust LMWH dose to achieve peak anti-Xa levels of 0.7 to 1.2 U/l ml 4 hours post dose

– If trough levels are subtherapeutic with therapeutic peak levels, dose 3 times daily

– Check anti-Xa levels weekly

Alternatively, dose-adjusted unfractionated heparin to achieve APTT ≥ twice the control levels can be used instead of LMWH