LOW-MOLECULAR-WEIGHT HEPARIN FOR OBSTETRIC THROMBOPROPHYLAXIS - EXPERIENCE OF 69 PREGNANCIES IN 61 WOMEN AT HIGH-RISK

OBJECTIVE: Our purpose was to investigate the use of low-molecular-wei ght heparin (enoxaparin, Clexane) for thromboprophylaxis in pregnancy. STUDY DESIGN: A prospective consecutive cohort of 61 pregnant women a t high risk oi: thromboembolism receiving antenatal thromboprophylaxis with enoxaparin (usually 40 mg, subcutaneously daily) in a total of 6 9 pregnancies was identified from the obstetric medicine clinic at Que en Charlotte's Hospital. Bone density measurements of the hip and lumb ar spine were taken in 26 women after 28 pregnancies within 16 months post partum. Nonparametric statistics were used for comparisons. RESUL TS: There were no episodes of antenatal thromboembolism. One woman (1. 6%] (receiving 20 mg of enoxaparin) had a pulmonary embolus post partu m. Heparin levels (anti-Xa assay) were greater with the 40 mg dose (me dian 0.09 U/ml) than with the 20 mg dose (median 0.03 U/ml) (p = 0.000 6) but were not affected by gestational age (r = -0.1, p = 0.14). Enox aparin had no effect on platelet count or on in vitro coagulation test s. Nine (32%) women had bone density in the spine or hip >1 SD below t he mean for age- and sex-matched controls. CONCLUSION: This, the large st study to date of low-molecular-weight heparin use in pregnancy, con firms previous reports that it is a safe and effective alternative to unfractionated heparin far obstetric thromboprophylaxis in high-risk w omen. Effects on bone demineralization require further investigation.