What anticoagulant is contraindicated in pregnancy due to teratogenicity?

From the Guidelines

Warfarin is the anticoagulant that is contraindicated in pregnancy due to its teratogenic effects. This vitamin K antagonist can cross the placenta and cause significant fetal harm, particularly during the first trimester when it may cause warfarin embryopathy (characterized by nasal hypoplasia and stippled epiphyses) and in the second and third trimesters when it can cause central nervous system abnormalities and fetal bleeding 1. For pregnant women requiring anticoagulation, low molecular weight heparins (LMWHs) such as enoxaparin are the preferred alternatives because they do not cross the placenta and have not been associated with teratogenicity or fetal bleeding. Unfractionated heparin is also considered safe during pregnancy for the same reason. The teratogenic effect of warfarin occurs because it inhibits vitamin K-dependent carboxylation of clotting factors and other proteins involved in fetal bone and cartilage development, while heparins work by enhancing antithrombin activity and do not affect these developmental processes.

Some key points to consider:

• Warfarin has a dose-dependent teratogenic effect, with a higher risk of embryopathy at doses greater than 5 mg/day 1.
• LMWHs are the preferred anticoagulants during pregnancy, with unfractionated heparin being a suitable alternative in certain situations 1.
• The use of warfarin during pregnancy is contraindicated due to its teratogenic effects, and alternative anticoagulants should be used instead 1.
• The management of anticoagulation during pregnancy requires careful consideration of the risks and benefits, and should be individualized based on the patient's specific situation 1.

In the context of the provided question, Warfarin is the correct answer as it is the anticoagulant that is contraindicated in pregnancy due to its teratogenic effects. Inferior vena cava filters, low-molecular-weight heparin, rivaroxaban, and unfractionated heparin are not contraindicated in pregnancy due to teratogenicity, although rivaroxaban's safety during pregnancy is not well established 1.

From the FDA Drug Label

Warfarin sodium tablets are contraindicated in women who are or may become pregnant because the drug passes through the placental barrier and may cause fatal hemorrhage to the fetus in utero. Furthermore, there have been reports of birth malformations in children born to mothers who have been treated with warfarin during pregnancy.

Embryopathy characterized by nasal hypoplasia with or without stippled epiphyses (chondrodysplasia punctata) has been reported in pregnant women exposed to warfarin during the first trimester

Central nervous system abnormalities also have been reported, including dorsal midline dysplasia characterized by agenesis of the corpus callosum, Dandy-Walker malformation, and midline cerebellar atrophy.

Although rare, teratogenic reports following in utero exposure to warfarin include urinary tract anomalies such as single kidney, asplenia, anencephaly, spina bifida, cranial nerve palsy, hydrocephalus, cardiac defects and congenital heart disease, polydactyly, deformities of toes, diaphragmatic hernia, corneal leukoma, cleft palate, cleft lip, schizencephaly, and microcephaly

Spontaneous abortion and stillbirth are known to occur and a higher risk of fetal mortality is associated with the use of warfarin.

Low birth weight and growth retardation have also been reported.

The anticoagulant Warfarin is contraindicated in pregnancy due to its teratogenicity 2. Key points include:

• Teratogenic effects: Warfarin can cause birth malformations, including embryopathy and central nervous system abnormalities.
• Fetal risks: Warfarin use during pregnancy is associated with a higher risk of fetal mortality, spontaneous abortion, stillbirth, low birth weight, and growth retardation.
• Contraindication: Warfarin is contraindicated in women who are or may become pregnant.

From the Research

Treatment Options for Pregnancy-Related Conditions

• The patient is at 32 weeks gestation and reports swelling and discomfort in her right leg, with an ultrasound revealing a noncompressible vein.
• The following treatment options are considered: Inferior vena cava filter, Low-molecular-weight heparin, Rivaroxaban, Unfractionated heparin, and Warfarin.

Contraindicated Treatment Due to Teratogenicity

• Warfarin is contraindicated in pregnancy due to its teratogenicity, as stated in studies 3, 4, 5, 6, 7.
• Warfarin can lead to spontaneous abortion, intrauterine death, nasal hypoplasia, hypoplasia of extremities, cardiac defects, scoliosis, and mental retardation when exposed in utero 4.
• The use of warfarin during pregnancy carries the potential for serious risks to the fetus, especially if administered during the first trimester or at term 7.
• Alternative anticoagulants such as unfractionated heparin or low molecular weight heparin are recommended during pregnancy, as they do not cross the placenta and are considered safer options 5.