Warfarin taken by a mother during pregnancy may cause serious defects in the fetus.


Types of adverse effect:

(1) warfarin embryopathy (with warfarin taken during first trimester, especially 6 and 12 weeks gestation)

(2) central nervous system (CNS) and ocular defects (with warfarin taken in all 3 trimesters)

(3) bleeding (with warfarin taken in third trimester)

(4) spontaneous abortion or stillbirth


Warfarin embryopathy:

(1) nasal hypoplasia and depression of the nasal bridge

(2) stippling of the uncalcified epiphyses (axial skeleton, proximal femur, calcaneus)

(3) shortened fingers, nail hypoplasia

(4) limb hypoplasias (less common than digital hypoplasia)

(5) CNS defects

(6) low birth weight


CNS and ocular defects:

(1) microcephaly

(2) hydrocephalus

(3) dorsal midline dysplasia (Dandy-Walker malformation, agenesis of the corpus callosum)

(4) optic atrophy (ventral midline dysplasia)

(5) microphthalmia

(6) mental retardation

(7) seizures

(8) hearing loss


Bleeding may be intrauterine, during delivery or postnatal. Intracranial bleeding may be significant.


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