THROMBOPROPHYLAXIS WITH LOW-MOLECULAR-WEIGHT HEPARIN (FRAGMIN) IN HIGH-RISK PREGNANCIES

Venous thromboembolic disease remains the commonest cause of maternal death. The management of thromboprophylaxis in high risk women during pregnancy is contentious. Low molecular weight heparins (LMW) have the oretical advantages compared with unfractionated heparin and warfarin but have been poorly studied in pregnancy. We report on the use of LMW heparin (Fragmin) as thromboprophylaxis in thirty four high risk preg nancies. All the women had a previous thrombosis or a thrombosis in th eir current pregnancy +/- a recognised thrombophilic state (eleven had the antiphospholipid syndrome). Fragmin was given subcutaneously to m aintain trough anti-Xa activity of 0.15-0.2 U/ml and 2 h post injectio n levels of 0.4-0.6 U/ml. The levels were checked monthly during pregn ancy. Most women required 5,000U Fragmin once daily during the first t rimester unless they were greater than 100 kg at the start of pregnanc y. The mean time for dosage increase was 20.5 week (S.D. 8.2). 26/34 p regnancies (76%) required 5,000 twice daily at the end of pregnancy. E pidural anaesthesia was managed by omitting Fragmin dose or inserting the needle 6 hours after the previous Fragmin injection. There were no thromboembolic events, thrombocytopenias or excessive haemorrhage. On e woman had osteoporotic vertebral collapse post partum, she had no ot her risk factors for osteoporosis. LWM heparin (Fragmin) appears to be efficacious in preventing recurrent thromboembolic disease in pregnan t women at high risk, but it is notable that osteoporotic fractures oc curred post partum in one woman. Further trials are required to determ ine optimal dosage and safety.