In a meta-analysis including 499 pregnancies, Lawley et al. examined maternal and perinatal outcomes in women with artificial heart valves. Less than 5% of women had the older, ball-and-cage type valves, making their data relevant to current practice. These authors reported a maternal mortality rate of 1.8% for mechanical valves, whereas no deaths were seen in women with bioprosthetic valves. Notably, in contrast to earlier studies no thrombosis-related deaths were identified in the current study. The authors appropriately
attribute this improvement to advances in the design of mechanical prostheses and modified anticoagulation regimens and monitoring.