Laboratory classification categories and pregnancy outcome in patients with primary antiphospholipid syndrome prescribed antithrombotic therapy

Thromb Res. 2009;123(3):482-7. doi: 10.1016/j.thromres.2008.03.012. Epub 2008 May 6.


Background: A relationship between antibody profile and pregnancy outcome in patients with a previous diagnosis of primary antiphospholipid syndrome (APS) has not been clearly documented.

Methods: Women attending our Center with primary APS characterized by the presence in the blood of one or more of the following: Lupus Anticoagulant (LA), IgG/IgM anticardiolipin (aCL), IgG/IgM anti-human beta2-Glycoprotein I (abeta2GPI) antibodies (confirmed after a minimum of 3 months) were considered eligible for this study. Women who became pregnant during the study period with the exception of those with congenital thrombophilia or other congenital abnormalities were included in our analysis. Primary outcome events, defined as early abortion or fetal death, were evaluated in relation to the laboratory classification category assigned to each patient at the time they were diagnosed with APS.

Results: A total of 97 pregnancies occurring in 79 primary APS patients during the study period were analyzed. Twelve out of 97 pregnancies were unsuccessful, 11 out of 65 (16.9%) in category I patients (more than one positive laboratory test) and 1 out of 32 (3.1%) in category II patients (single positive test; adjusted hazard ratio 1.9; 95% CI, 0.2 to 18.9, p=0.6). Pregnancy loss took place in 10 out of 19 pregnancies (52.6%) in women belonging to category I with triple positivity and in 1 out of 46 pregnancies (2.2%) in patients with double positivity. The rate of pregnancy loss was more frequent in the 19 pregnancies of patients with triple positivity than in the 46 pregnancies of double positive patients (adjusted hazard ratio 23, 95% CI, 1.3 to 408, p=0.03).

Conclusion: Poor pregnancy outcomes occur more frequently in category I than in category II primary APS patients. However, it has been seen that a greater predictability is achieved when category I patients are grouped into triple and double positivity states.

MeSH terms

  • Adult
  • Antibodies, Anticardiolipin / blood
  • Antiphospholipid Syndrome / classification
  • Antiphospholipid Syndrome / complications*
  • Antiphospholipid Syndrome / drug therapy*
  • Antiphospholipid Syndrome / immunology
  • Female
  • Fibrinolytic Agents / therapeutic use*
  • Humans
  • Immunoglobulin G / blood
  • Immunoglobulin M / blood
  • Infant, Newborn
  • Lupus Coagulation Inhibitor / blood
  • Pregnancy
  • Pregnancy Complications / classification
  • Pregnancy Complications / drug therapy*
  • Pregnancy Complications / immunology
  • Pregnancy Outcome
  • Retrospective Studies
  • beta 2-Glycoprotein I / antagonists & inhibitors
  • beta 2-Glycoprotein I / immunology


  • Antibodies, Anticardiolipin
  • Fibrinolytic Agents
  • Immunoglobulin G
  • Immunoglobulin M
  • Lupus Coagulation Inhibitor
  • beta 2-Glycoprotein I