SAN DIEGO – Low molecular weight heparin does not appear to reduce the risk of recurrent placenta-mediated pregnancy complications in women with prior such complications, according to Marc Rodger, MD.
“It’s time to put the needles away for pregnant patients,” he said at the biennial summit of the Thrombosis & Hemostasis Societies of North America.
Doug Brunk/MDedge News
Dr. Mark Rodger
The pathophysiology of placenta-mediated pregnancy complications includes placental thrombosis. Thrombophilias predispose to the development of thrombosis in slow-flow circulation of the placenta. “It’s possible that the etiology mix of placental-mediated pregnancy complications includes thrombophilias, and by extension, that anticoagulants would prevent these complications,” said Dr. Rodger, a senior scientist at the hospital and professor at the University of Ottawa.
In a study from 1999, researchers demonstrated that patients with pregnancy-mediated placental complications were 8.2 times more likely to develop thrombophilia, compared with controls (N Engl J Med. 1999;340:9-13). “But as with positive initial case-control studies, subsequent work downplayed this association,” Dr. Rodger said. “Now, we’re at a point where we recognize that thrombophilias are weakly associated with recurrent early loss, late pregnancy loss, and severe preeclampsia ([odds ratio] of about 1.5-2.0 for all associations), while thrombophilias are not associated with nonsevere preeclampsia and small for gestational age.”
Currently, low-molecular-weight heparin (LMWH) is the preferred pharmacoprophylaxis in pregnancy. Unfractionated heparin, meanwhile, requires b.i.d. or t.i.d. injections, and has a 10-fold higher risk of heparin-induced thrombocytopenia and a greater than 10-fold higher risk of osteoporotic fracture. Warfarin is teratogenic antepartum and inconvenient postpartum, while direct oral anticoagulants cross the placenta and enter breast milk.
Downsides of LMWH include the burden of self-injections and costs of over $10,000 per antepartum period, Dr. Rodger said. Common side effects include minor bleeding and elevated liver function tests, and it complicates regional anesthetic options at term. Uncommon side effects include major bleeding, skin reactions, and postpartum wound complications, while rare but serious complications include heparin-induced thrombocytopenia and osteoporotic fractures.