Thromboprophylaxis and pregnancy: two randomized controlled pilot trials that used low-molecular-weight heparin.
OBJECTIVE
The purpose of this study was to conduct pilot studies for large randomized controlled trials to compare low-molecular-weight heparin with placebo for antenatal thromboprophylaxis (trial 1), and for thromboprophylaxis after cesarean delivery (trial 2).


METHODS
Multicenter randomized controlled trials (trial 1, 23 units; trial 2, 8 units) were conducted. Pregnant women at increased risk for thromboembolic disease were eligible for trial 1; women who underwent cesarean delivery were eligible for trial 2. The interventions were once daily injections of low-molecular-weight heparin or placebo. Primary outcomes were as follows: trial 1, confirmed symptomatic thromboembolic events and symptomatic osteoporotic fractures; trial 2, confirmed symptomatic thromboembolic events and wound complications.


RESULTS
Sixteen women were recruited for trial 1; 1 woman in the placebo group had a symptomatic thromboembolic event. One hundred forty-one women were recruited for trial 2; 1 woman in the low molecular weight heparin group had a symptomatic thromboembolic event.


CONCLUSIONS
Poor recruitment indicates that large-scale trials using these designs would be difficult. Collection of data on the number of women that are eligible and the reasons for nonrecruitment in future trials of these interventions would allow a better understanding of the reasons for poor recruitment.
Gates
Simon
S
National Perinatal Epidemiology Unit, University of Oxford, Old Campus Road, Oxford OX 3 7LF, United Kingdom. simon.gates@perinat.ox.ac.uk
Brocklehurst
Peter
P
Ayers
Sarah
S
Bowler
Ursula
U
D000328:Adult; D002585:Cesarean Section; D017984:Enoxaparin / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D005343:Fibrinolytic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D010024:Osteoporosis / Q000139:chemically induced; D018579:Patient Selection; D010865:Pilot Projects; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000517:prevention & control*; D020246:Venous Thrombosis / Q000517:prevention & control*
D017984:Enoxaparin; D005343:Fibrinolytic Agents