Bone mineral density during long-term prophylaxis with heparin in pregnancy.

OBJECTIVE: We studied the effect of long-term heparin treatment on bone mass during pregnancy. STUDY DESIGN: Thromboprophylaxis with heparin was given to 39 women during pregnancy for a mean of 28 weeks and for an average of 6 weeks post partum. Bone mineral density measured with single-photon absorptiometry of the distal and ultradistal parts of the forearm was determined at the time of the start of heparin treatment (mean, twelfth week of gestation), immediately post partum, and on average 7 weeks post partum. The mean dosage of heparin was 17,300 IU/day. A control group of 34 normal pregnant women was studied for comparison. RESULTS: In women treated with heparin, there was almost a 5% reduction in trabecular bone during pregnancy (p < 0.01) and an insignificant recovery post partum. There were no significant changes in bone mass during pregnancy or in the puerperium in the control group. CONCLUSION: Long-term treatment with heparin during pregnancy is associated with bone loss, but indications of reversible changes are observed.

Osteoporotic fractures and the recurrence of thromboembolism during pregnancy and the puerperium in 184 women undergoing thromboprophylaxis with heparin.

OBJECTIVE: To study the effect of long-term treatment during gestation with heparin on the incidence of osteoporotic fractures and thromboembolic recurrence. STUDY DESIGN: Long-term subcutaneous prophylaxis with heparin twice daily in pregnancy was prescribed for 184 women, during a decade because of an increased risk of thromboembolism. The dosage of heparin was adjusted to anti-factor Xa activity or activated partial thromboplastin time and different regimens were given, depending on the risk of recurrence. RESULTS: For the total group the mean dosage of heparin ranged from 13,000 to 40,000 IU per 24 hours (mean 19,100 IU per 24 hours), and the average duration of treatment was 25 weeks. Symptomatic osteoporotic fractures of the spine occurred post partum in four women, for whom the mean dosage of heparin ranged from 15,000 to 30,000 IU per 24 hours (mean 24,500 IU per 24 hours), and the duration of treatment ranged from 7 to 27 weeks (mean 17 weeks). In spite of prophylaxis with heparin, thromboembolic complications occurred in five women. They had either nonsatisfactory concentrations of heparin according to our regimen or were later diagnosed as having a coagulation disorder known to increase the risk of thromboembolism. CONCLUSION: Osteoporotic vertebral fractures were found in 2.2% of the women, and a relationship to the amount of heparin was indicated, although fractures were not avoided during low-dose, short-term prophylaxis. Recurrence of thromboembolism occurred in 2.7% of the patients, but if a strict heparin adjustment had been performed, recurrence could probably have been prevented.

Thrombosis prophylaxis in pregnancy with use of subcutaneous heparin adjusted by monitoring heparin concentration in plasma.

Twenty-six pregnant women were given prophylactic heparin treatment because of previous thromboembolic complications. The mean duration of treatment was 25 weeks (range, 6 to 32 weeks). The amount of heparin was adjusted to a plasma concentration of 0.08 to 0.15 IU/ml, measured as anti-factor Xa activity. This effect was compared with that on activated partial thromboplastin time. The average dose was 16,400 IU/24 hours or 225 IU/kg of body weight per 24 hours. When the plasma concentration was within the stipulated range, the dose was 234 IU/kg of body weight/24 hours. No significant prolongation of activated partial thromboplastin time was found in two thirds of the samples. Blood coagulation was either not activated or only slightly activated, as verified by a low level of fibrinopeptide A. Platelet counts and antithrombin III levels were generally not depressed. No thromboembolic complications occurred during the pregnancies or puerperium. Bleeding during delivery was not increased. No fractures of the spine caused by osteoporosis were found on radiologic examination post partum.