***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objective To pilot a protocol for a national multicentre r and omised trial in which a low molecular weight heparin will be compared with placebo for prevention of venous thrombotic events occurring within six weeks after caesarean section Venous thromboembolism remains an important cause of maternal mortality . For women at risk during pregnancy , the recommended venous thromboembolismprophylaxis is unfractionated heparin . Low molecular weight heparins , such as dalteparin , also may be suitable , but r and omised trials have not been performed . Pregnant women ( 105 ) with confirmed previous or current thromboembolism were r and omised to receive either unfractionated heparin twice daily ( mean 20569 IU/day ) or dalteparin once daily ( mean 4631 IU anti-factor Xa units/day ) subcutaneously for thromboprophylaxis during pregnancy and postpartum period . Recurrence of venous thromboembolism and safety of treatments were assessed . Dalteparin administered once daily was safe and effective in thromboprophylaxis during pregnancy and postpartum Venous thromboembolism remains an important cause of maternal mortality . In a r and omised open study , 44 pregnant women with confirmed previous or current thromboembolism were r and omised to receive either low-molecular-weight heparin , dalteparin ( N = 21 ) once daily subcutaneously or unfractionated sodium heparin ( UF heparin , N = 23 ) twice daily subcutaneously for thromboprophylaxis during pregnancy and puerperium . Bone mineral density ( BMD ) in the lumbosacral spine was measured with dual X-ray absorptiometry ( DEXA ) 1 , 6 , 16 , 52 weeks and , if possible , 3 years after delivery . BMD values were also compared with those of healthy , delivered women ( N = 19 ) . Mean BMD of the lumbar spine was significantly lower in the unfractionated heparin group compared with the dalteparin and with the control groups ( repeated measures ANOVA p = 0.02 ) . BMD in the dalteparin group did not differ from BMD of healthy delivered women . Multiple logistic regression analysis revealed that therapy was the only independent factor influencing BMD at weeks 16 and 52 . Therefore we recommend use of dalteparin instead of UF heparin for long-term thromboprophylaxis during and after pregnancy 
    Output:
    
There is no evidence from r and omised controlled trials on the effectiveness of anticoagulation for deep vein thrombosis in pregnancy .