Bone density changes in pregnant women treated with heparin: a prospective, longitudinal study

Heparin plus aspirin significantly improves the live birth rate of women wi th primary antiphospholipid syndrome. Osteopenia is a major concern of long -term heparin therapy. We studied prospectively the bone mineral density (B MD) changes during pregnancy and the puerperium in 123 women with primary a ntiphospholipid syndrome treated with low-dose aspirin and subcutaneous low -dose heparin (46 women took unfractionated heparin and 77 took low-molecul ar-weight heparin). Lumbar spine, neck of femur and forearm BMD were measur ed, using dual energy X-ray absorptiometry, at 12 weeks gestation, immediat ely postpartum and 12 weeks postpartum. The mean heparin duration was 27 we eks (range 22-29). During pregnancy, BMD decreased by 3.7% (P < 0.001) at t he lumbar spine and by 0.9% (P < 0.05) at the neck of femur with no signifi cant change at the forearm. Lactation was associated with a significant dec rease in the lumbar spine and neck of femur BMD. There was no significant d ifference in BMD changes between the two heparin preparations. No woman suf fered a symptomatic fracture. Long-term heparin treatment during pregnancy is associated with a small but significant decrease in BMD at the lumbar sp ine and neck of femur. This decrease is similar to that previously reported to occur in untreated pregnancies.