Why is warfarin contraindicated in pregnancy?

Why is warfarin contraindicated in pregnancy?

• A. It crosses the placenta and can cause fetal bleed
• B. It causes neural tube defects
• C. It increases risk of fetal alloimmunization
• D. It enhances placental transfer of insulin

Answer: (D)

Warfarin is avoided in pregnancy because it crosses the placenta and inhibits the fetus’s vitamin K–dependent clotting factors. This can lead to fetal coagulopathy and a range of birth defects if exposure occurs, especially during the first trimester (warfarin embryopathy). The fetus is particularly vulnerable to bleeding and developmental abnormalities, and there is an increased risk of miscarriage or fetal death with maternal warfarin use. Because of this, alternative anticoagulation with heparin (which does not cross the placenta) is used during pregnancy, with warfarin typically resumed only after delivery. The concern is about placental transfer of the drug and its fetal effects, not about insulin.

Warfarin is avoided in pregnancy because it crosses the placenta and inhibits the fetus’s vitamin K–dependent clotting factors. This can lead to fetal coagulopathy and a range of birth defects if exposure occurs, especially during the first trimester (warfarin embryopathy). The fetus is particularly vulnerable to bleeding and developmental abnormalities, and there is an increased risk of miscarriage or fetal death with maternal warfarin use. Because of this, alternative anticoagulation with heparin (which does not cross the placenta) is used during pregnancy, with warfarin typically resumed only after delivery. The concern is about placental transfer of the drug and its fetal effects, not about insulin.