Pregnancy increases the risk of thromboembolic complications and death in women with mechanical heart valves. It is accepted that therapeutic anticoagulant during pregnancy is required, although there are no ideal agents without both maternal and fetal risk. The main maternal risk is valve thrombosis, even despite therapeutic anticoagulation. The main fetal risk is increased fetal loss.
Vit K antagonists (warfarin) have the lowest thromboembolic risk, but there is risk of fetal embryopathy if used in first trimester, and an ongoing risk of fetal loss throughout pregnancy. LMW heparin does not cross placenta but has a higher thromboembolic risk even if therapeutic levels are maintained.
To achieve acceptable outcomes for both mother and fetus close monitoring throughout pregnancy is required with involvement of Cardiology, Haematology and Obstetric teams. Alternatives of Vit K antagonists and/or low molecular weight heparin and ± additional aspirin are discussed. Current European and American Guidelines and local recommendations will be given.