Long-term dalteparin in pregnancy not associated with a decrease in bone mineral density: substudy of a randomized...

The risk of decreased bone mineral density (BMD) with prophylactic dose long-term low-molecular-weight heparin (LMWH) is unknown.

We sought to determine whether long-term prophylactic dalteparin in pregnancy leads to loss of BMD.

Patients in a substudy of an ongoing multicenter randomized trial investigating the effect of antepartum dalteparin prophylaxis on pregnancy outcomes in thrombophilic pregnant women were randomized to either dalteparin 5000 U s.c. daily until 20 weeks and then 5,000 U s.c. q12 h until >37 weeks or to the control group. The primary outcome was absolute spine BMD at six weeks postpartum.

Of 77 patients eligible for the BMD substudy, 62 were analyzed. 33 patients received a mean of 212 days of dalteparin in the intervention group. 29 patients received a mean of 38 days of postpartum dalteparin in the control group. There was no difference in mean BMD between the intervention (1.11 g cm(-2)) and the control groups (1.14 g cm(-2)). Similarly, there was no difference in T-scores; the difference of -0.34 (95% confidence interval -0.93 to +0.25) in favor of the control group excludes a clinically important increase in fracture risk.

Our results suggest that the use of long-term prophylactic dalteparin in pregnancy is not associated with a significant decrease in BMD.

ISRCTN87441504 at http://www.controlled-trials.com.