Short-term low-dose heparin plus bedrest impairs bone metabolism in pregnant women.

Objective: To assess the osteoporotic risk of short-term low-dose heparin plus bedrest in pregnancy.

Study Design: In a prospective case-control study, 10 pregnant women on bedrest receiving prophylactic unfractionated heparin 10,000 IU per day for 7-46 days pre-study and 28 days per-study were compared with 6 normal pregnant controls of similar maternal and gestational age and 10 nonpregnant women of similar age. Serum ionised calcium, 1,25-dihydroxyvitamin D(3), osteocalcin, and urinary calcium/creatinine ratio were determined three times at 2-week intervals.

Results: 1,25-Dihydroxyvitamin D(3) was lower in the treated group than in pregnant controls throughout (P<0.03). Osteocalcin was lower at study start than end in both pregnant groups (P<0.05), and lower in the treated group than in either pregnant (n.s.) or nonpregnant controls (P<0.005). Calcium/creatinine ratio differences were non significant (n.s.).

Conclusion: Short-term low-dose heparin plus bedrest suppresses 1,25-dihydroxyvitamin D(3) and osteocalcin levels in pregnancy.