Background and aims: Pregnancy in women with a prosthetic heart valve is considered high risk, primarily due to the need for effective anticoagulation. However, data on the relationship between anticoagulation practices and pregnancy outcomes are very limited.
Methods: The Registry of Pregnancy and Cardiac disease is a global registry that prospectively enrolled pregnancies in women with a prosthetic heart valve between January 2018 and April 2023. Detailed data on anticoagulation, including dosage and monitoring, and cardiovascular, pregnancy, and perinatal outcomes were collected.
Results: In total, 613 pregnancies were included of which 411 pregnancies were in women with a mechanical valve and 202 were in women with a biological valve. The chance of an uncomplicated pregnancy with a live birth in women with a mechanical valve was 54%, compared with 79% in women with a biological valve (P < .001). Thromboembolic and haemorrhagic complications most frequently occurred when low-molecular weight heparin (LMWH)-based regimens were used. Valve thrombosis occurred in 24 (6%) women, and a prosthetic valve in mitral position was associated with valve thrombosis (odds ratio 3.3; 95% confidence interval 1.9-8.0). A thromboembolic event occurred in 12 (10%) women with anti-Xa monitoring and in 9 (21%) women without (P = .060). Foetal death occurred in 20% of all pregnancies.
Conclusions: More favourable outcomes were found in women with a biological valve compared with a mechanical valve. In women with a mechanical valve, the use of LMWH was associated with an increased risk of thromboembolic complications. A mitral prosthetic valve was identified as a predictor for valve thrombosis. The benefit could not be confirmed nor refuted, in terms of reduced thromboembolic events, from using anti-Xa level monitoring in women on LMWH.
Keywords: Anticoagulation; Biological valve; Mechanical valve; Pregnancy; Valve thrombosis.
© The Author(s) 2025. Published by Oxford University Press on behalf of the European Society of Cardiology.