To study the efficacy of thromboprophylaxis with low molecular weight heparin (LMWH) in pregnant women with one previous venous thromboembolic event (VTE). Secondary aims were to study the long-term risk of secondary recurrence, bleeding and obstetric complications.
A prospective national study of long-term LMWH thromboprophylaxis in Sweden.
All hospitals in Sweden during January 1998-December 2002,
Pregnant women with one previous VTE and controls drawn from the Swedish Medical Birth Registry. The women were cross-matched with the Swedish Hospital Discharge Register to identify all recurrences and to ascertain the annual risk of recurrence.
Recurrence of VTE, bleeding complications at delivery and obstetric complications.
326 of 393 registered women could be evaluated. The relative risk reduction in VTE was 88%. There was an absolute increased risk of VTE during the thromboprophylaxis period: 1.2% compared to 0.2% among controls (p