***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: Women with a history of venous thromboembolism ( VTE ) , thrombophilia or both may be at increased risk of thrombosis during pregnancy , but the optimal management strategy is not well defined in clinical guidelines because of limited trial data . A strategy of risk assessment and heparin prophylaxis was evaluated in pregnant women at increased risk of VTE . In a prospect i ve trial ( Efficacy of Thromboprophylaxis as an Intervention during . Gravidity [ EThIG ] ) , 810 pregnant women were assigned to one of three management strategies according to pre-defined risk factors related to history of VTE and thrombophilic profile . Low-risk women ( group I ) , received 50 - 100 IU dalteparin/kg body weight/day for 14 days postpartum , or earlier when additional risk factors occurred . Women at high ( group II ) or very high risk ( group III ) received dalteparin from enrollment until six weeks postpartum ( 50 - 100 IU and 100 - 200 IU/kg/day , respectively ) . Objective ly confirmed , symptomatic VTE occurred in 5/810 women ( 0.6 % ; 95 % confidence interval [ CI ] , 0.2 to 1.5 % ) ( group I , 0 of 225 ; II , 3/469 ; III , 2/116 ) . The rate of serious bleeding was 3.0 % ( 95 % CI , 1.9 to 4.4 % ) ; 1.1 % ( 95 % CI , 0.5 to 2.2 % ) was possibly dalteparin-related . There was no evidence of heparin-induced thrombocytopenia , one case of osteoporosis , and rates of miscarriage and stillbirth were similar to previous , retrospective studies . Risk-stratified heparin prophylaxis was associated with a low incidence of symptomaticVTE and few clinical ly important adverse events . Antepartum heparin prophylaxis is , therefore , warranted in pregnant women with idiopathic thrombosis or symptomatic thrombophilia Intravenous heparin followed by oral anticoagulant therapy ( e. g. with coumarin ) is still the most widely used treatment for  deep venous thromboembolism .  Self-administered subcutaneous injections of heparin have been thought of as a promising alternative to coumarin , but the high doses required for ongoing prophylaxis have raised concerns about the possible development of bone disease . Certainly , long-term heparin therapy has been reported to cause osteoporosis in both laboratory animals and humans . This study aim ed to compare the efficacy and safety of unfractionated ( UF ) heparin with that of a low molecular weight heparin ( Fragmin , Kabi Pharmacia ) in the prevention of recurrent deep venous thrombosis ( DVT ) and pulmonary embolism ( PE ) in a consecutive series of patients with contraindications to coumarin therapy . The patients comprised 40 men and 40 women , aged between 19 and 92 years ( mean age , 68 years ) . They had all previously been diagnosed as having acute DVT and had been treated with conventional doses of heparin while in hospital . All patients had at least one of the following conditions : recent blood loss ( either spontaneous or during admission while receiving heparin therapy ) ; active gastroduodenal ulcer disease ; psychological or physical inability or unwillingness to underst and and accept the need for regular laboratory monitoring during coumarin treatment ; chronic alcoholism ; dementia ; pregnancy ; recent neurosurgery , and pericardial effusion ; or were over 80 years of age . They were r and omly allocated to receive either UF heparin , 10,000 IU s.c . b.d . , or Fragmin , 5000 IU anti-Factor Xa s.c . b.d . , for a period of 3 - 6 months . ( ABSTRACT TRUNCATED AT 250 WORDS We have previously reported that long-term therapy with warfarin is effective for preventing recurrent venous thromboembolism in patients with proximal-vein thrombosis but that there is an appreciable risk of hemorrhage . To determine whether that risk could be reduced without a loss of effectiveness , we r and omly allocated 96 patients with proximal-vein thrombosis to a group receiving  less intense anticoagulant therapy , with a mean prothrombin time of 26.9 seconds using the Manchester comparative reagent ( corresponding Simplastin time , 15 seconds ) , or a group given more intense therapy , with a mean Simplastin time of 19.4 seconds ( corresponding prothrombin time 41 seconds with the Manchester comparative reagent ) ( P less than 0.001 ) . Two of 47 patients ( 4 per cent ) in the less intensely treated group had hemorrhagic complications , as compared with 11 of 49 patients ( 22 per cent ) in the more intensely anticoagulated group ( P = 0.015 by the two-tailed test ) . This difference was due to minor bleeding episodes . The frequency of recurrent venous thromboembolism was low in both groups ( 2 per cent ) . Our findings indicate that less intense anticoagulant therapy is associated with a low frequency of recurrent venous thromboembolism ( 2 per cent ) and a reduced risk of hemorrhage OBJECTIVE To assess the maternal response to low molecular weight heparin during pregnancy , by estimation of plasma anti-Xa activity , at three specified gestation points and in the nonpregnant state . METHODS A longitudinal , prospect i ve , observational study was set in a tertiary referral recurrent miscarriage clinic . Twenty-four women , attending consecutively , were invited to participate and gave informed consent . Each woman had a history of recurring pregnancy loss and positive preconception screening for antiphospholipid syndrome . After confirmation of a viable pregnancy all subjects began taking 5000 IU of dalteparin once daily subcutaneously . Serial measurement of plasma anti-Xa activity after administration of dalteparin was performed at three st and ard gestation points ( 12 , 24 , and 36 weeks ) and in the nonpregnant state ( 6 weeks postpartum ) . RESULTS Peak anti-Xa levels occurred at 4 hours postbolus in pregnancy , as compared with 2 hours in the nonpregnant state . The mean anti-Xa levels at 12 , 24 , and 36 weeks ' gestation were significantly reduced , at 2 hours postinjection , as compared with the nonpregnant state ( P < .001 , P < .01 , P < .001 , respectively ) . The lowest dose – response curve was at 36 weeks ' gestation . A repeated- measures analysis of variance found a significant difference ( P < .05 ) between the 36-week group and the postterm group but not between any of the other groups . CONCLUSION During pregnancy , differences in the pharmacokinetics of low molecular weight heparin were observed , with an overall reduction in anti-Xa activity . On the basis of this study it is question able to extrapolate dosing and lack of dose monitoring , in pregnant women , using data derived from a nonpregnant OBJECTIVE The purpose of this study was to compare the use of low-dose aspirin alone with heparin and low-dose aspirin in the treatment of the antiphospholipid antibody syndrome . STUDY DESIGN A prospect i ve , single-center trial included 50 patients who were alternately assigned to treatment . Each patient had at least three consecutive spontaneous pregnancy losses , positive antiphospholipid antibodies on two occasions , and a complete evaluation . Data were compared by chi(2 ) analysis and Fisher 's exact test . RESULTS Viable infants were delivered of 11 of 25 ( 44 % ) women treated with aspirin and 20 of 25 ( 80 % ) women treated with heparin and aspirin ( p < 0.05 ) . There were no significant differences between the low-dose aspirin and the heparin plus low-dose aspirin groups with respect to gestational age at delivery ( 37.8 + /- 2.1 vs 37.2 + /- 3.4 weeks ) , number of cesarean sections ( 18 % vs 20 % ) , or complications . CONCLUSION Heparin plus low-dose aspirin provides a significantly better pregnancy outcome than low-dose aspirin alone does for antiphospholipid antibody-associated recurrent pregnancy loss OBJECTIVES To determine if a prophylactic dose of dalteparin , 5000 IU daily , and if the adjusted-weight dalteparin therapeutic dose of 100 IU/kg twice daily are appropriate in pregnancy . METHOD Anti-Xa activity levels were used to assess prophylactic  ( 33 women ) and therapeutic  ( 15 women )  dalteparin dosage throughout pregnancy . Analysis of variance was used and P-values less than 0.05 were considered statistically significant . RESULTS In the prophylactic group , anti-Xa activity levels did not vary significantly throughout pregnancy ( P=0.15 ) . The initial dalteparin dose was modified on the first anti-Xa activity measurement in eight women , whose weight was statistically different from those remaining on the initial dose ( P<0.001 ) . The adjusted-weight therapeutic dalteparin dose induced adequate anti-Xa activity levels . CONCLUSIONS Dalteparin , 5000 IU daily , is suitable for most pregnant women and does not need to be modified in the third trimester . A therapeutic dalteparin dose adjusted according to pregnancy weight is appropriate BACKGROUND The aim of this study was to assess the effect of long-term low molecular weight heparin ( LMWH ) on bone mineral density ( BMD ) during pregnancy . METHODS Fifty-five patients with recurrent miscarriage and known thrombophilia ( antiphospholipid syndrome ) were followed through pregnancy in an ethically approved prospect i ve observational study . All women had dual energy X-ray absorptiometry ( DEXA ) scans at the lumbar spine ( L1-L4 ) performed within 6 months prior to conception and in the immediate post-natal period , within 6 weeks of delivery . LMWH ( 5000 U/day ) plus low-dose aspirin was commenced after a positive urine pregnancy test and continued throughout pregnancy and after delivery until 6 weeks post-partum . A group of 20 volunteers with recurrent miscarriage , not requiring any treatment intervention , acted as controls and were monitored in an identical fashion . RESULTS Characteristics were not significantly different between treated patients and controls . Both groups showed a similar loss in lumbar spine ( L1-L4 ) BMD by the end of the pregnancy [ LMWH 4.17 % or 0.045 g/cm(3 ) , 95 % confidence interval ( CI ) 0.036 - 0.062 versus control 3.56 % or 0.043 g/cm(3 ) , 95 % CI 0.027 - 0.059 ] . However , the difference in bone loss between the groups was not statistically significant ( 0.002 g/cm(3 ) , CI -0.0124 to 0.00865 ; P = 0.88 ) . No patient suffered vertebral fracture . CONCLUSIONS Bone loss associated with the use of long-term LMWH is not significantly different from physiological losses during pregnancy Mechanical valve thrombosis is a life-threatening event , while pregnancy is associated with a hypercoagulable state . Thus , in pregnant women with mechanical valves , adequate anticoagulation becomes even more critical . This prospect i ve study was conducted to establish a uniform anticoagulation regimen for these women . A total of 250 pregnancies in 245 women with mechanical heart valves were evaluated . The patients were divided into 2 groups : group 1 ( n = 150 ) took oral warfarin throughout pregnancy and group 2 ( n = 100 ) received subcutaneous heparin in the 1st trimester and oral warfarin for the other trimesters . Both groups received heparin at the time of delivery . There were no coumarin-induced fetal malformations . Minor thromboembolic episodes took place in 5 women in group 1 and 3 in group 2 . Valve thrombosis occurred in 1 woman in group 2 and led to 1 maternal death in this series . The incidence of spontaneous abortion was similar between the groups . We conclude that warfarin is safe and convenient to use during pregnancy . The teratogenic effects of warfarin during the 1st trimester are overstated , and switching to heparin is not m and atory BACKGROUND Women with a history of venous thromboembolism may be at increased risk for venous thromboembolic events during pregnancy . In these women , the decision to give or withhold heparin in the antepartum period is controversial , because accurate estimates of the frequency of recurrent thromboembolic events if antepartum heparin is withheld are not available . METHODS We prospect ively studied 125 pregnant women with a single previous episode of venous thromboembolism .  Antepartum heparin was withheld , but anticoagulant therapy was given for four to six weeks post partum . Our primary objective was to determine the rate of antepartum recurrence of venous thromboembolism . Laboratory studies were performed to identify thrombophilia in 95 women . RESULTS Three of the 125 women ( 2.4 percent ) had an antepartum recurrence of venous thromboembolism ( 
    Output:
    
There is no evidence from r and omised controlled trials to evaluate the effectiveness and safety of different methods of administering subcutaneous heparin ( UFH or LMWH ) to pregnant women