Low Molecular Weight Heparin and/or Aspirin in Prevention of Habitual Abortion

Background: The prevalence of spontaneous abortions is 1000-1500/10000 pregnancies per year meaning that 10-15% of all pregnancies will end in an abortion; 1/10 of these abortions are recurrent (1 % of all pregnancies). In about half of women with habitual abortions (HAB) hereditary (F V Leiden, F II (prothrombin) mutation, Protein C, S deficiency and anti-thrombin) or acquired (antiphospholipid antibodies) thrombophilia are observed. Efficacy of the medical treatment of patients with a history of HAB has yet to be completely demonstrated. We have recently shown that low-molecular-weight heparin (LMWH) is as effective as unfractionated heparin in prevention of thromboembolic complications in pregnant women and causes less bleeding complications (UFH) and has no osteoporotic effect. LMWH could be safer than UF-heparin during long treatment periods (7-8 months).

Study design: Randomised placebo controlled multicenter study.

Centers: Helsinki (2), Oulu (1), Stockholm (1), Leiden (1)

Number of patients per study: 90 patients per group, 270 altogether

Timetable: Starting 2/2002, finishing 31.12.2007

Drugs:

HABENOX 1 and 2: Study groups Group 1 : Enoxaparin 40 mg+ placebo, Group 2: Enoxaparin 40 +ASA 100 mg, Group 3: ASA.

HABENOX 3: Study groups Group 1: Enoxaparin 40 twice daily+ placebo o.d., Group 2: Enoxaparin 40 mg twice daily +ASA 100 mg o.d.

Time frame: one year since entering the study with primary end-points:livebirths (> 37 weeks of gestation) and premature livebirths (> 24, but <37 weeks of gestation)

Primary end-points: Pregnancy outcome: livebirths (>37 weeks of gestation), premature livebirths (> 24, but <37 weeks of gestation) Secondary end-points: Bleeding complications, intrauterine growth retardation (<-2SD), pre-eclampsia, abruptio placentae,

Inclusion criteria: Three or more consecutive abortions of first trimester (ad h 12+6 wks) or two second trimester abortions (ad h 13 wks-23+6 wks) or one third trimester abortion (24 weeks or more) with one first-second trimester abortions. Depending on the thrombophiliatest (tested before pregnancy) result the patients will included in one of the three sub-studies:

1. HABENOX 1: those who have one thrombophiliatest positive: F V Leiden (heterozygote) or protein C or S deficiency, or anticardiolipin antibodies (low to moderate level), prothrombin gene mutation, or high level of F VIII.
2. HABENOX 2: those with thrombophilia test negative
3. HABENOX 3:those with "high risk" thrombophilia: positive combined thrombophilia, F V Leiden (homozygote), anticardiolipin antibodies (high level >40) , lupusanticoagulant, or AT III deficiency.

During next pregnancy the patient, with inclusion criteria fulfilled, will be asked to sign informed consent and she will be allocated into one of the three treatment groups. The treatment will be started before 7 weeks of gestation. At baseline and follow-up visits plasma, serum and 20 ml morning urine will be frozen (analysed later for antithrombin, protein S, C, APC ratio, PAI1, PAI2, U-PAR, D-dimer, thrombin-antithrombin (TAT) complex, CRP, TNFalpha(+ receptor), ICAM, VEGF(+receptor), urinary stabile metabolites of thromboxane and prostacyclin.

Follow-up: US/Doppler + obstetric check-up at 8, 10, 14, 18, 24, 28, 32 and 36 weeks of gestation Ending: In the group of combined medication, tablets will be stopped at 36 weeks of gesta-tion. LMWH will be started in all patients after delivery and continued 6 weeks postpartum.