Treatment of antiphospholipid antibody syndrome (APS) in pregnancy: a randomized pilot trial comparing low molecular weight heparin to unfractionated heparin

J Obstet Gynaecol Can. 2004 Aug;26(8):729-34. doi: 10.1016/s1701-2163(16)30644-2.


Objective: To compare low molecular weight heparin (LMWH), specifically dalteparin, to unfractionated heparin (UFH) for the treatment of antiphospholipid antibody syndrome (APS) in pregnancy.

Methods: In a tertiary referral centre, 28 women met the 1999 International Consensus Criteria for APS, based on their obstetrical history and APS serology. The women were randomized, using a random numbers table with blocks of 12, to receive either prophylactic dosing of dalteparin or UFH starting either preconceptionally or early in pregnancy. All women also received low-dose acetylsalicylic acid, started preconceptionally. The primary outcome was a live birth. The secondary outcomes were maternal and fetal complications.

Results: Of the 14 women who received the LMWH, dalteparin, and the 14 women who received UFH, 1 woman in each group did not conceive. Nine of the 13 women (69%) given dalteparin had a successful pregnancy (95% confidence interval [CI], 39-91%), compared to 4 out of the 13 women (31%) in the UFH group (95% CI, 9-61%). Nine women in total had spinal or epidural anaesthesia, and there were no complications overall.

Conclusion: Dalteparin may be an effective alternative to UFH for treatment of APS in pregnancy. A multicentre randomized trial is needed to determine benefit-to-risk ratios for the use of dalteparin and UFH to treat this high-risk obstetrical condition. Pharmacokinetic and pharmacodynamic studies are also recommended to maximize therapeutic response and minimize toxicity.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anticoagulants / therapeutic use*
  • Antiphospholipid Syndrome / drug therapy*
  • Aspirin / therapeutic use
  • Dalteparin / therapeutic use*
  • Female
  • Heparin / therapeutic use*
  • Humans
  • Pilot Projects
  • Preconception Care
  • Pregnancy
  • Pregnancy Complications / drug therapy*
  • Pregnancy Outcome


  • Anticoagulants
  • Heparin
  • Aspirin
  • Dalteparin