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.