Objective: Our purpose was to evaluate the subclinical occurrence of heparin-induced osteoporosis in pregnancy, by means of bone densitometry.
Study design: A prospective, consecutive cohort of 14 pregnant women requiring heparin therapy and 14 pregnant controls matched for age, race, and smoking status was identified by 20 weeks' gestation at a university medical center. Proximal femur bone density measurements were taken at baseline, immediately post partum, and 6 months post partum in the cases and controls. Vertebral measurements were also obtained on both groups immediately post partum and 6 months post partum. Bone density as a function of heparin dosing and duration was examined. Nonparametric statistical tests were used for all comparisons.
Results: Five of 14 cases (36%) had a > or = 10% decrease from the baseline proximal femur measurements to immediate postpartum values versus none of the 14 matched controls (p = 0.04). Mean proximal femur bone density measurements also decreased in the cases (p = 0.01); this difference continued to be statistically significant 6 months post partum (p = 0.03). No dose-response relationship could be demonstrated.
Conclusion: Heparin adversely affected bone density in about one third of exposed patients.