What do systematic reviews say?

Low molecular weight heparin vs UFH

LMWH probably leads to lower incidence of recurrent VTE1 (3 months compared with UFH (moderate certainty).

• Fixed dose subcutaneous low molecular weight heparins versus adjusted dose unfractionated heparin for the initial… 2017 · Cochrane Headline outcomes only
  OR 0.71 [0.56, 0.9]
  16 studies · 6661 participants
  Moderate