Aspirin = enoxaparin for prevention of recurrent miscarriage

Clinical Question

How do aspirin and enoxaparin compare for the prevention of unexplained recurrent miscarriage?

Bottom Line

Daily treatment with aspirin or enoxaparin (Lovenox) each results in a high live birth rate for women with history of unexplained recurrent miscarriages. The lack of a control group is an important limitation of this study. (LOE = 1b-)


Dolitzky M, Inbal A, Segal Y, Weiss A, et al. A randomized study of thromboprophylaxis in women with unexplained consecutive recurrent miscarriages. Fertil Steril 2006;86:362-366.  [PMID:16769056]

Study Design

Randomized controlled trial (nonblinded)






Outpatient (specialty)


This study enrolled women (n=104) with history of at least 3 consecutive miscarriages. The authors excluded women whose miscarriages had known causes, including cardiovascular disease, thromboembolism, and abnormal results of any of the following; karyotype of either parent, glucose tolerance test, toxoplasmosis serology, hysterosalpingogram or hysteroscopy, thyroid function, serum prolactin, antinuclear antibodies, antiphospholipid antibodies, and hereditary thrombophilias. Women were randomized to either 100 mg aspirin daily, or 40 mg enoxaparin subcutaneously daily. The study was not blinded, but allocation was concealed and analyses was by intention to treat. Live births occurred in 84% of women taking aspirin and 82% of women taking enoxaparin (NS). There were no differences in preterm births or infant Apgar scores. There was 1 infant with growth retardation in the enoxaparin group. There were 3 women with preeclampsia, all in the aspirin group. There was 1 case of infant testicular torsion and 1 infant with hypoglycemia and convulsions, both in the aspirin group. The study was too small to detect statistical differences in any of these outcomes. The was no placebo arm for this study, which the authors defended by stating that women would not want to enroll in a study in which they might be randomized to placebo. Historical control patients were cited with a 60% live birth rate after 3 consecutive miscarriages and a 40% live birth rate after 4 losses.