Fetal warfarin syndrome

Overview

Fetal Warfarin Syndrome (FWS) is a rare congenital disorder resulting from prenatal exposure to the anticoagulant drug warfarin during pregnancy, especially during the first trimester. Warfarin interferes with vitamin K-dependent processes that are essential for normal fetal development. The syndrome is characterized by a specific set of craniofacial abnormalities, skeletal defects, and central nervous system anomalies. FWS is part of a broader category known as warfarin embryopathy and is entirely preventable by avoiding warfarin during pregnancy.

Causes

FWS is caused by maternal use of warfarin during pregnancy. Warfarin crosses the placenta and disrupts fetal vitamin K metabolism, which is critical for bone development and coagulation. Key risk factors include:

• Use of warfarin during the first trimester: Greatest risk of structural abnormalities occurs between weeks 6–12 of gestation.

• High dosage or prolonged use: Increases the risk and severity of fetal abnormalities.

• Underlying maternal conditions: Women with mechanical heart valves or thrombophilia syndromes often require anticoagulation during pregnancy.

Symptoms

Infants with Fetal Warfarin Syndrome display a constellation of characteristic features. These include:

Craniofacial Abnormalities

• Depressed nasal bridge (flat nose)

• Short nose with a broad tip

• Epicanthal folds (skin folds at the inner corners of the eyes)

• Hypertelorism (wide-set eyes)

• Microcephaly (small head circumference)

Skeletal Abnormalities

• Stippled epiphyses (punctate calcifications at the ends of bones)

• Limb hypoplasia or shortening

• Vertebral and rib abnormalities

Neurological and Other Complications

• Hydrocephalus or brain malformations

• Intellectual disability or developmental delay

• Seizures

• Ocular anomalies (e.g., optic atrophy)

• Increased risk of intracranial bleeding

Diagnosis

Diagnosis of Fetal Warfarin Syndrome is based on a combination of maternal history, physical findings, and imaging studies. Diagnostic steps include:

• Maternal medication history: Confirming warfarin use during early pregnancy.

• Physical examination: Identification of craniofacial and skeletal abnormalities at birth.

• Radiographic imaging: X-rays show stippled epiphyses and skeletal malformations.

• Neuroimaging: CT or MRI to assess for brain anomalies or bleeding.

• Developmental assessments: To monitor cognitive and motor development.

Treatment

There is no specific cure for Fetal Warfarin Syndrome. Treatment is symptomatic and supportive, depending on the type and severity of malformations. Management may involve:

• Surgical intervention: For structural abnormalities such as limb defects or hydrocephalus.

• Physical and occupational therapy: To support motor development and functional mobility.

• Speech and developmental therapy: For children with communication delays or intellectual disabilities.

• Regular monitoring: Ongoing assessments of neurological, orthopedic, and developmental health.

• Multidisciplinary care: Collaboration between pediatricians, neurologists, orthopedic surgeons, and therapists.

Prognosis

The prognosis for children with Fetal Warfarin Syndrome depends on the extent of the abnormalities and the success of early interventions. Some children may have only mild skeletal deformities, while others may face significant cognitive and physical disabilities. With proper supportive care, many individuals can achieve functional independence. However, prevention remains the best approach, warfarin should be avoided during pregnancy, especially in the first trimester. Safer alternatives like low molecular weight heparin (LMWH) are typically recommended for anticoagulation in pregnant women.