Prolonged low-molecular-weight heparin use during pregnancy and subsequent bone mineral density

- Prolonged use of LMWH during pregnancy was not associated with subsequent decrease in BMD.
- Incidence of osteopenia was similar between the LMWH-group and the control-group.
- No osteoporosis or osteoporotic fractures existed.

IntroductionIn contrast to unfractionated heparin (UFH), use of low-molecular weight heparin (LMWH) during pregnancy has not been reported to be associated with a significant decrease in bone mineral density (BMD). The aim of this study was to investigate whether long-term use of LMWH during pregnancy is associated with subsequent decrease in BMD or with increased number of osteoporotic fractures.Materials and methodsIn this observational cohort study BMD was measured by dual energy X-ray absorptiometry (DEXA) 4-7 years after the last delivery in 152 women. Ninety-two women had prolonged LMWH-exposure during pregnancy - 75 as prophylaxis and 17 as treatment for venous thromboembolic event (VTE). Dalteparin and enoxaparin were the LMWH-preparations used. Sixty women without LMWH-exposure served as controls. A questionnaire about lifestyle factors and medical history was filled out by the subjects.ResultsLumbar spine BMD in the LMWH users was lower than that in the controls both in the prophylactic group (1.22 g/cm2 vs. 1.27 g/cm2; p = 0.03), and in the treatment group (1.20 g/cm2 vs. 1.27 g/cm2; p = 0.07). BMD in femoral neck did not differ between the LMWH-users and controls. However, after adjusting for potential confounding factors, LMWH-exposure did not remain associated with decreased BMD in lumbar spine. Use of contraceptive pills was positively associated with BMD in lumbar spine. Incidence of osteopenia was 13% in the LMWH-group and 8% in the control-group, (p = 0.4). No osteoporosis or osteoporotic fractures were found.ConclusionsProlonged use of LMWH during pregnancy was not associated with subsequent decrease in BMD, osteopenia, osteoporosis, or osteoporotic fractures.