Establishing or Excluding a Diagnosis of Fetal Valproate Spectrum Disorder is a Multi-layered Process.

Background In 2017/2018, the Health Products Regulatory Authority issued new guidance on the prescription of Sodium Valproate (VPA) to female patients of reproductive age. A review was initiated of VPA exposed individuals to identify whether previously unascertained cases of VPA related Embryopathy could be identified. Methods Forty patients under twenty-three years of age were reviewed. Results Eleven (27.5%) new cases of Fetal Valproate Spectrum Disorder (FVSD) were identified. Twenty-four (60%) cases were felt not to satisfy diagnostic threshold for this teratogenic disorder. Five (12.5%) cases were indeterminate. Six of the forty patients (15%) had an alternative genetic cause of developmental delay established. Conclusion There is increased awareness regarding avoidance of VPA use in women of childbearing age. An equal awareness is warranted that developmental delay in the context of VPA exposure in pregnancy does not necessarily constitute a diagnosis of FVSD but that other competing diagnostic hypotheses have to be considered.