What is the optimal management of pregnant women with valvular heart disease in pregnancy?

Women with mechanical heart valves require anticoagulation during pregnancy. Continued anticoagulation with coumadin throughout the first trimester can result in foetopathic effects in 6.4% (95% CI, 4. 6-8.9%) of cases. Replacement of warfarin with heparin between 6 and 12 weeks' gestation eliminates this risk. Although warfarin does cross the placenta, adverse central nervous system effects associated with its use are very few. Warfarin is effective in preventing maternal thromboembolic complications, while the effectiveness of heparin in preventing valve thrombosis is unproven. The optimal management (grade C2 recommendation) of women with mechanical heart valves may involve the use of warfarin throughout pregnancy except for two time periods - between 6 and 12 weeks' gestation and after 36 weeks of gestation. During these times, adjusted-dose unfractionated heparin should be used to rigorously maintain a therapeutic mid-interval activated partial thromboplastin time of 2.0 to 2.5 times the control. The additional use of low-dose aspirin should be considered, particularly in women with high-risk valves, women with previous transient ischaemic attacks and/or strokes, and women with atrial fibrillation.