Blood Home > Arixtra and Pregnancy

The FDA has assigned a pregnancy Category B classification to Arixtra (fondaparinux), meaning that it is generally considered safe for pregnant women to take it. Animal studies indicate that even high doses of this medicine do not increase the risk of birth defects. Also, the drug does not cross the placenta to a significant extent, so it is not expected to cause problems for a developing fetus.

Is Arixtra Safe During Pregnancy?

Arixtra® (fondaparinux sodium) is a prescription medication approved to treat and prevent blood clots. Based on the results of animal studies, it is generally thought to be safe for use during pregnancy.

What Is Pregnancy Category B?

The U.S. Food and Drug Administration (FDA) uses a pregnancy category system to classify the possible risks to a fetus when a specific medicine is taken during pregnancy. Pregnancy Category B is given to medicines that have not been adequately studied in pregnant humans, but do not appear to cause harm to the fetus in animal studies. Medications that have been shown to be safe for use in pregnancy in humans (but have caused problems in laboratory animals) are also given a Category B rating.
Arixtra is thought to be safe for use during pregnancy for several reasons. In studies in rats and rabbits, Arixtra did not increase the risk of birth defects or other problems, even at very high dosages. Also, Arixtra does not cross the placenta (to the developing fetus) to a significant extent in humans, so it is not expected to significantly increase the risk of bleeding in the fetus.
However, there is very little experience with the use of this medication during pregnancy. Heparin or low molecular weight heparin medications are usually the preferred anticoagulants for pregnant women. In rare instances, however, a pregnant woman may not be able to take heparin or a low molecular weight heparin, usually due to an allergy or severe reaction. In such cases, Arixtra may be a good alternative, at least theoretically.
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
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