What are the risks of heparin use during pregnancy?
Heparin carries the risk of heparin-induced thrombocytopenia and osteopenia during pregnancy, which may lead to symptomatic vertebral fracture. Additionally, the pharmacokinetic changes of pregnancy result in a shorter half-life and lower peak plasma concentration of heparin compounds, with the need to titrate doses in order to keep the mid-interval aPTT (6 h post dose $ twice control values). Therefore, the use of low molecular weight heparin (LMWH) is preferred over unfractionated heparin (UFH) as subcutaneous treatment during pregnancy.