Which anticoagulant is frequently used to prevent thrombosis in pregnancy?

Low molecular weight heparin (LMWH) is frequently used to prevent thrombosis in pregnancy due to its safety profile and effectiveness. During pregnancy, there is an increased risk of venous thromboembolism due to physiological changes such as enhanced coagulation and venous stasis. LMWH is preferred because it does not cross the placenta and is less likely to cause harm to the developing fetus compared to other anticoagulants.

Additionally, LMWH has predictable pharmacokinetics, allowing for easier management with less frequent dosing compared to unfractionated heparin. While it is important to monitor certain parameters, the risk of complications is significantly reduced, making LMWH a suitable choice for pregnant patients, especially those with a history of thrombosis or other risk factors.

Other anticoagulants listed are not the first-line options for pregnancy. For instance, warfarin is contraindicated because it can cross the placenta and is associated with teratogenic effects. Aspirin is generally used for different indications in pregnancy, such as preventing preeclampsia rather than as a primary anticoagulant. Clopidogrel's use in pregnancy is also limited and generally not recommended for routine prophylaxis against thrombosis.