<prompt> LMW heparin is preferred over unfractionated heparin because:LMW heparin directly inhibit thrombin whereas unfractionated heparin acts activation of anti thrombinLMW heparins have higher risk of causing bleedingLMW heparin can be given subcutaneously as well as orallyLMW heparin has consistent bioavailability.  <response>: LMW heparin inhibit factor Xa only and have a weak effect on thrombin , aPTT, or CT are not prolonged. Heparin acts by activation of antithrombin III. LMW heparin is given subcutaneosly due to better bioavalability.LMW heparin have subcutaneous bioavalability of 70 - 90. From medical pharmacology padmaja 4th edition Page no 337 