Oral Presentation Society of Obstetric Medicine of Australia and New Zealand ASM 2015

Anticoagulation in pregnancy for indications other than VTE (#2)

Claire McLintock 1
  1. National Women's Hospital, Auckland, AUCK, New Zealand

Low molecular weight heparin (LMWH) is recommended for use in treatment and prevention of venous thromboembolism in pregnancy. It is safe and effective in this clinical setting. Its role in prevention of pregnancy-related problems has been the focus of much attention with a number of studies assessing the impact of LMWH in improving outcomes in women with histories of recurrent pregnancy loss, preeclampsia, SGA infants, placental abruption, singly and in combination. It is suggested that rather than antithrombotic role, perhaps it may have an effect by modifying placenta trophoblast invasion, extravillous trophoblast differentiation or promote angiogenesis in placental villi.

Randomised clinical studies of LMWH in women with antiphospholipid antibodies and pregnancy complications have mainly focused on women with recurrent pregnancy loss and despite conflicting results most practitioners advise the used of LMWH for women with obstetric complications of antiphospholipid syndrome (APS). None of the four studies of women with unexplained recurrent pregnancy loss, not due to APS, have shown improved pregnancy outcomes. LMWH is not recommended for use in this setting.

Studies of LMWH use in other placental-mediated complications such as preeclampsia, SGA pregnancies, placental abruption have also shown conflicting results with benefit in more severe, early onset disease.

Confusion about the clinical impact is compounded by the decision of some clinical researchers to include women in their studies who have conditions which may not necessarily share the same underlying pathological process – for example why should women who have a previous provoked DVT be at risk of developing preeclampsia or fetal growth restriction? Trials with a more homogenous study population with women who have conditions with a similar pathological mechanism such as those with preeclampsia and intrauterine growth restriction i.e. the EPPI study or the HEPEPE study of women with severe early onset preeclampsia are currently underway and may be better placed to provide answers to these important clinical questions.

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